Methods and apparatus for measuring and monitoring an anchoring operation

ABSTRACT

Novel techniques and equipment for anchoring a boat include sensing and measuring the real time rate and length of rode release based on detecting real time changes in the angular position of a windlass by computer vision using a portable computing device. Rode release is also detected using novel methods based on sensing sound, rode chain movement, and sensing acceleration and/or motion. The apparatus can include software operable to provide safe anchoring based on monitoring real times values of the rate and length of rode release, comparing these values to the speed and position of the boat, and providing local and remote status and alarm information to crew members.

CROSS-REFERENCES TO RELATED APPLICATIONS

This present application claims the benefit of U.S. ProvisionalApplication No. 63/009,443 filed Apr. 13, 2020.

FIELD OF THE INVENTION

The present disclosure relates generally to the art of affixing a boatto a position in a body of water and more particularly relates tomethods and apparatus based on computer vision, audio sensors,micro-mechanical sensors, digital signal processing, artificialintelligence, and/or augmented reality to monitor, adjust, and regulatethe anchoring of a boat in a body of water.

BACKGROUND

Marine vessels can range in size from 6-meter-long recreational powerboats to 350-meter-long aircraft carriers. All require anchoring (forexample see FIG. 1) to maintain the position of a boat 100 in a body ofwater 105 and prevent it from being moved by, water currents and forces110. A boat operator (“skipper”) can be tasked with setting an anchor115 at a designated geophysical anchor site 120. The anchor is attachedto a boat near its bow 135 by a tether 125, called a rode, which can bea rope or chain. The rode can be made from a variety of materials suchas nylon, polyester, kevlar, iron, steel, and others, depending on theapplication. The anchor can become embedded in a seabed 130 and tensiontransmitted through the connecting rode can hold the bow. The boat 100may move (see for example, FIG. 2) along an arc 205 drawn around theanchor site 120. The radius of the arc depends on the rode length andthe amount of tension required to support the various forces 110 thatwind, currents, and/or waves apply to the boat 100.

A skipper must ensure that the boat 100 does not collide with nearbyobjects such as another boat 215, rocks 220, coral, and/or a marina orpier as the boat moves along the arc 205 (as shown in FIG. 2). Anchorcontrol of boat position is commonly used in a body of water 105 wherethe water level is sufficiently shallow to permit an anchor 115 that isset in the seabed to be attached to the boat with a rode 125 (seabedwill be understood to mean the bottom of any body of water including alake, river, ocean, etc). In some circumstances, a skipper/crew may usetwo or more anchors respectively attached to different positions on theboat, for example bow and stern, to hold both of these points inrelatively fixed positions.

In the process of anchoring, an anchor site is selected by taking intoconsideration water depth, prevailing wind/current, and proximity ofnearby objects (for example other boats, rocks, shore, marina, etc.).Depending upon weather, boat size and other factors, a boat crewreleases a length of anchor rode that is approximately 6-8 times thedepth of water at the anchor site. Generally, the boat is first moved toposition where its bow is above the selected anchor site, beforestarting release of the anchor rode. After the descending anchor reachesthe sea bed, the boat generally moves downwind from the anchor site,stern first, and additional rode is continually released rode as theboat moves. Anchor rode must be released at a faster rate than the boatspeed to prevent ‘dragging’ the anchor along the seabed from theselected site. At the end of this process, a crew may test the successof a set anchor operation by powering the boat in reverse for severalseconds, before removing power (neutral) to see whether the tension fromthe rode causes the boat to spring forward in the direction of theanchor site. This method and test are not reliable and the result is aboat not securely anchored.

Anchor rode is released or retrieved with equipment comprising arotating pulley device called a windlass (WL). A vertical WL 300, asshown in FIG. 3, is so called because its axis is perpendicular to thedeck to which it is mounted. The rode (chain in this case) 125 isreleased as the WL turns counter clockwise, and it is retrieved (alsoknown as gathering) when it rotates clockwise. The chain is fed througha WL gypsy 305 with sprockets engaging each link in the chain. Awindlass capstan (WLC) 310 at the top of the WL has a winch socket 315at its center. FIG. 4 shows an expanded view of the gypsy 305 having adiameter 405, showing details of the sprockets that lock onto chainlinks 125 as the gypsy rotates.

Another vertical WL 300 is shown in FIG. 5 mounted to boat deck 505.Rode 125 and anchor 115 are in a fully retrieved position. A WL can bepowered from a boat's battery bank. The WL motor is usually a singlespeed high torque motor having one push button control 510 that turnsthe motor on in a rotation direction to release rode 125 (and the anchor115), and another push button control 515 to run the motor in theopposite direction to gather rode 125 and retrieve the anchor 115. Thesecontrols cannot change motor speed. FIG. 6 shows a horizontal WL 300mounted below a boat deck 605.

Anchor position is can be maintained through friction with a seabed. Theforces in play applied to an anchored boat are illustrated in FIG. 7. Aboat 100 is fixed under tension applied by rode 125 running betweenwindlass bow 135 and anchor 115 which has been set at the seabed 130.The mass of the anchor and rode result in a gravitational force F_(g)705 perpendicular to the seabed that is proportional to their combinedmasses according to EQ. 1:F _(g) =G*(m _(anchor) +m _(rode))*m _(earth) /R ² _(earth)  EQ. 1Where G is the gravitational constant and R_(earth) is the radius of theearth. The gravitational force on the anchor ultimately results in aforce of friction F_(f) 710 acting in the opposite direction of wind andcurrent forces 110 on the boat 100 according to:F _(f) =μ*F _(g)  EQ. 2where the parameter μ is an environment-dependent coefficient offriction. The gravitational force F_(g), and hence the frictional forceF_(f), is proportional to the sum of the anchor m_(anchor) and releasedrode m_(rode) mass resting on the sea bed. That mass must be sufficientto result in a frictional force exceeding the forces of the wind andcurrent 110 on the boat in order to keep the boat secure in itsanchorage. This frictional force F_(f) increases with the length of arode having contact with the seabed. Hence it is often desirable to havea substantial length of rode laying along the seabed which can addtangential restraining force for a boat. In FIG. 7, chord 720 of lengthH drawn between the ends of the catenary formed by rode 125 whichconnects bow 135 to the anchor 115, forms an hypotenuse of a righttriangle having an interior angle θ relative to the horizontal plane ofthe sea, leg 715 with a length equal to the water depth (d), and leg 725equal to the horizontal distance L along the seabed between the boat andthe anchor site (e.g. the point where the tangent to the catenary curvehas flattened to within about 3 degrees of horizontal) 725. It can beseen:θ=arctan(d/L),  EQ. 3L/H=cos(θ)  EQ. 4

In an ideal hypothetical scenario, a helmsman might move a boat on thesurface of a body of water into a predetermined anchoring position abovepreselected anchoring site, and maintain that position while a crewmember releases a length of rode substantially equal to the distance dshown in FIG. 7, such as is necessary to lower the anchor vertically andlay on the seabed. In this fictitious scenario, once the anchor is infrictional contact with the seabed underneath the boat, a helmsman canback up the boat while a suitable length of additional rode issimultaneously released. However, those skilled in the will appreciatethat this hypothetical scenario is not practical at least because theboat is subject to drift while the anchor is being lowered, such thatits geophysical position moves away from the anchoring site. Hence localdepth of the seabed as well as the point at which the anchor finallyreaches the seabed in reality can be unknown, and the anchor isgenerally not visible through many feet of water. Furthermore, acombined force arising from the weight of the anchor and the forcesapplied from an appreciable length of rode may be necessary to set theanchor in the seabed securely. This often requires the rode to havesufficient length form a catenary curve that has flattened to withinabout 3 degrees of horizontal (e.g. θ≤3°) in the neighborhood of theanchor.

As a practical matter, owing to these uncertainties, rode release isstarted when the boat reaches a preselected set anchor position. Therode is released as fast as practical in order to minimize horizontalforce on the anchor as a helmsman powers the boat backward, so as toeffectuate tension that will set the anchor after it makes contact withthe seabed. It is important that the rate of rode release must farexceed the boat speed in order to minimize any horizontal displacementof the anchor position before the anchor makes effective contact withthe seabed (e.g. minimize dragging). As is generally depicted in FIG. 7,the resulting catenary formed by the rode should ultimately have arelatively long leg “L” (725) reflective of the relatively high rate ofrode release relative to the speed of the boat 100 as it is pilotedduring the anchoring operation. In typical instance, the length of rodereleased during a set anchor operation, e.g. the length of catenary 125,can be about 6 to 8 times the water depth d.

An anchor that has not been set properly can be problematic and/ordangerous. A reliable anchoring process depends on moving the boat tocompensate for drift while releasing the anchor. It can be quitedifficult to simultaneously control boat movement and chain releasespeeds with respect to one another. If the boat moves faster than therate of chain release after the anchor touches the seabed, the anchormay drag along the seabed surface without locking into the targetanchoring site.

Anchor dragging can occur even when the boat is in a protected bay. Aboat approaching a shore from the sea can be anchored, at a site havinga suitable depth for safe anchor, near the shore. Here, a boat willtypically drop anchor and move backwards away from the shore towarddeeper water as the chain is released from the bow. However, if there isan unexpected change in ratio between water depth and chain length, theanchor may be dragged into deeper water. The crew may believe it hasdeployed a sufficient length of chain whereas the boat may actually becoupled to an untethered anchor in deep water. This is an unsecuresituation. It will be apparent that reliable knowledge of the waterdepth and measurements of the length of chain released are crucial.

Boat speed can be a critical variable as well. If a boat backs up tooslowly, the chain may not apply enough stress to set the anchorproperly. In an extreme case, this can result in chain piling up on theseabed. Alternatively, the chain may be laid along the sea bed without aset anchor so as to apply little or no tension on the boat and anchor.Ordinarily this is not as dangerous as anchor dragging, but wind andcurrents can cause the boat to drift.

From this simplified description of a set anchoring operation it will beclear to those practicing the art that it is important for multiple crewmembers to monitor the water depth, the length and rate of anchor rodereleased, the speed of a boat, and the distance of boat from a selectedanchor site throughout an anchoring operation. However, no devicesand/or methods operable to effectuate these functions simultaneouslyhave been available.

Many boats have a simple sonar sensor embedded in the boat hull tomonitor water depth. Sonar sensors are required to ensure that the boatdoes not suffer damage when navigating shallow waters.

Global Navigation Satellite Systems (GNSS) chart plotters, that arecommonly found on sea faring boats, have built in mapping capabilities.These instruments can overlay the current position of the boat onnavigation charts and track boat speed. GNSS chart plotter manufacturerssuch as RayMarine (http://www.raymarine.com, retrieved on Feb. 23,2021), can trigger an alarm when the boat position exceeds apredetermined distance from a selected location. These devices can tracka boat position as the boat swings through an arc 205 defined by therode 125 and anchor site 120 as shown in FIG. 2. There are smartphoneapplications such as Aqua Map having similar functionality(http://www.globalaquamaps.com/Anchor_Alarm.html, retrieved on Feb. 23,2021).

Prior art techniques to measure chain length during the course of a setanchor operation include counting periodic marks either painted on orattached to equally spaced rode chain links. Maintenance requires a crewto stretch the rode along the boat deck and paint chain links at regularintervals along its length. Alternatively, crew may attach plastic clipsto chain link at equal intervals along the rode length. By counting thenumber of marked links as the rode is released a crew may estimatereleased rode length. In practice, crew members are easily distractedduring an anchoring operation and can easily lose count. Apart beingerror prone, the markings themselves are problematic. Paint weathers andfades when exposed to the elements and corrosive environment of the sea.Chain links grind against the seabed or each other during use and/orstorage. In real world environments the paint quickly wears off, makinglink counting difficult. Plastic clips wear at least as quickly,frequently breaking in either the chain locker (cabinet where the rodeis stored) or as the rode passes through the WL gypsy. For these, andother reasons, counting marked links is a technique rarely used in realworld anchoring applications.

New boats smaller than 30 meters in length, seldom have chain counters.However, retrofit WL chain counters are available from a number ofmanufacturers. Retrofit chain counters such as described in U.S. Pat.No. 6,374,765, use an attached magnet to sense a WL revolution each timethe magnet traverses a sensor. Installation of these devices isintrusive, difficult, and laborious. Besides challenges associated withdisassembling the WL and mounting the retrofit chain counter, a magnetmust be epoxied into a hole in the gypsy and a sensor must be a recessin the base of the WL before the WL is re-assembled and reattached tothe deck of a boat. Installation also requires cables be run to theboat's electric breaker panels and addition of cockpit and mountingdisplay hardware in the cockpit. These chain counters must be calibratedby manually measuring the length of rode released in proportion to thenumber of WL revolutions.

A prior smart phone art application, “Anchor Chain Counter App”,purported to measure rode release based on receiving sound patternsemanating from a WL with the smartphone microphone. It was reported tohave been offered on the online Google Play Store before being removed.(https://www.cruisersforum.com/forums/f118/anchor-chain-counter-smartphone-app-157394.html,dated May 12, 2015 retrieved on Feb. 23, 2021,https://m.apkpure.com/anchor-chain-counter/com.berndbrinkmann.counterretrieved on Mar. 28, 2021). However, the application could not measureany chain length reliably, or distinguish between chain release andretrieval.

Accordingly, it can be seen that there has been a long felt need for lowcost methods and devices to effectuate reliable and secure anchoring ofa boat by monitoring the length and rate of rode release, water depth atthe anchoring site, boat velocity, and the distance between a boat andan anchoring site in real time.

SUMMARY

Methods and apparatus for sensing and measuring real time changes inangular rotation of a windlass (WL), the rate and length of anchor roderelease, boat speed, and boat position during a boat anchoring operationare described. A relationship between the length and/or incremental rateof anchor rode release, boat speed and/or distance from an anchoringsite can be automatically evaluated, and critical values of therelationship can be used trigger an alarm condition. Various anchoringparameters and/or alarms can be displayed in a user interface and sentover a wireless network and displayed to a plurality of remote crewmembers having networked computing devices.

More particularly specific embodiments of methods and apparatus fordetermining a length of rode traversing a gypsy of a windlass in realtime during an anchoring operation are disclosed. There is a methodbased on accumulating a sum of incremental rotation angles of a windlassin real time with a computer comprising capturing digital images of thewindlass that have a trackable feature on the uppermost surface at earlyand later times. The digital images are saved in a computer memory. Thismethod includes a step of sensing a respectively early and a laterangular position of the trackable feature in the early and later digitalimages, using a computer vision algorithm. It also includes a step ofdetecting a difference between the later and the early angular positionsof the trackable feature on the windlass in real time with a computer,where the said difference between the positions is a signed incrementalrotation angle. Furthermore, the method includes adding the signedincremental rotation angle to the sum of incremental rotation angles;and multiplying the sum of incremental rotation angles by a calibrationfactor defining a proportionality between a length of rode release andwindlass rotation angle.

In an aspect of the method, the length of rode release is a total lengthof rode that has been released and/or gathered during an entireanchoring operation. In another aspect, the digital images are capturedwith a camera having a digital image sensor. A further aspect comprisesa step of providing the trackable feature on a visible upper surfacefixed to the windlass, where the trackable feature is selected fromamong a marking, material adhering to the visible upper surface forminga pattern, a light emitting device, an area of the upper surface havingalphanumeric characters, and an area of the upper surface havingdistinct contrast. A still further aspect has steps operable todetermine the calibration factor.

An embodiment of steps operable to determine the calibration factorcomprises supporting the digital camera in a position where a field ofview of the camera encloses a windlass capstan and a portion of a rodechain emerging from the windlass, and providing a software having anuser interface. The application having the user interface is operable toshow digital camera video images from the camera in real time on a touchscreen display, and superimpose a center alignment marking for windlasscapstan and a central alignment marking for the rode chain on the touchscreen display showing digital camera video images of the capstan andemerging rode chain. The user interface is further operable to receiveuser gestures for positioning and/or scaling the center alignmentmarking for the windlass capstan onto a center of the windlass capstanin the digital camera video images. The user interface is also operableto receive user gestures for positioning and/or scaling the centralalignment marking for the emerging rode chain onto a midline of theemerging rode chain in the digital camera video images. Furthermore, themethod comprises computing an effective windlass gypsy diameter based onthe positioning and/or scaling of the center and central alignmentmarkings.

Another aspect of the above method is based on accumulating a sum ofincremental rotation angles and includes performing the capturing, thesensing, the detecting a difference, the adding, and the multiplyingwith a mobile computing device comprising a digital camera, tangiblemedia operable to store data and instructions, a processor, atouch-sensitive display screen, an speaker, and a wireless networkcommunication interface. The mobile computing device is selected fromamong a smartphone, a tablet computing device, and a portable computer.

There is also a method of determining a length of rode chain traversinga gypsy of a windlass and emerging from the windlass in real time duringan anchoring operation disclosed. The method comprises providing anumber of rode chain links in a unit length of the rode chain,supporting a digital camera in a position where the length of rode chainemerging from the windlass is within the field of view of the digitalcamera, capturing a sequence of digital video images from the digitalcamera, and saving the digital video images of the sequence in computermemory, and analyzing each digital video image in relation to previousdigital video image(s) of the sequence. The method is performed with acomputer having instructions and data operable to perform an opticalflow analysis algorithm useful to detect a number of chain links passingthrough the field of view. This method further comprises performingcomputer instructions operable to divide the number of chain linkspassing through the field of view by the number of chain links per unitlength of the rode chain.

This disclosure also provides computer readable tangible media havingstored data and instructions for a mobile computing device to performsteps operable to measure a length of rode traversing a windlass gypsyof a boat and a rate of rode being released and/or gathered by thewindlass gypsy in a boat anchoring operation. The steps comprisecapturing an early and a later digital image of the windlass atrespectively early and later times using a digital camera, and savingthe early and later digital camera images in a computer memory. Thesteps further comprise sensing an early and a later angular position ofa trackable feature on the windlass in the respective early and laterdigital images with a computer vision algorithm, and detecting adifference between the later and the early angular positions of thetrackable feature on the windlass in real time using a computer. Thedifference between the positions is a signed incremental rotation angle.There are still further steps including adding the signed incrementalrotation angle to the sum of incremental rotation angles, andmultiplying the sum of incremental rotation angles by a calibrationfactor defining a length of rode that is released proportionate to anangle of windlass rotation.

An aspect of the aforementioned computer readable tangible media furthercomprises stored data and instructions operable for a processor of themobile computing device to perform further steps operable to determinethe calibration factor. The further steps comprise providing usernotification operable to direct a user to support a digital camera in aposition wherein video images from the digital camera comprise thewindlass capstan and a portion of a rode chain emerging from thewindlass. There are further steps of displaying the digital imagescomprising the windlass capstan and a portion of a rode chain emergingfrom the windlass in a screen display, superimposing alignment markingson the windlass capstan and rode chain in the screen display, receivinguser input operable to move and/or scale the superimposed alignmentmarkings wherein a first alignment marking is positioned at the centerof the windlass capstan and a second alignment marking is centered inthe emerging rode chain in the screen display, and computing aneffective windlass gypsy diameter based on the positioning and/orscaling of the first and the second alignment markings. There is also anembodiment of this aspect of the computer readable tangible media wherethe screen display is a touch screen display and user input comprisesgestures on the touch screen display.

Another embodiment of the tangible media above further comprises storeddata and instructions operable for a processor of the mobile computingdevice to acquire real time boat location coordinates from real timeposition sensing means embedded in the mobile computing device. The dataand instructions are also operable to determine a real time speed of theboat based on the boat location coordinates, determine a real time totaldistance of the boat from an anchor site based on the acquired boatlocation coordinates, display first information comprising a comparisonof the boat speed to the rate of rode being released in real time in ahuman interface of the screen display, determine a real time totallength of rode released from the boat based on the product of thecalibration factor and the sum of the incremental rotation angles,display second information comprising a comparison of the total lengthof rode released from the boat to the total distance of the boat fromthe anchor site in real time in a human interface of the screen display,and send the first and/or second information over a wireless network toa remote computing device. By these steps, a remote helmsperson,skipper, and/or crew member having the remote computing device canreceive the first and second information in real time. These furtherdata and instructions are also operable to evaluate a relationshipcomprising one or more parameters selected from among the real timevalues of boat speed, the rate of rode being released, the total lengthof rode released from the boat, and the total distance of the boat fromthe anchor site, and compare the value of the predetermined relationshipto a predetermined alarm limit value. If the alarm limit value isexceeded, the data and instructions are operable to provide a visualand/or audible alarm on the mobile device, and send a signal and/or dataover the wireless network to a remote mobile device. The remote mobiledevice has remote data and remote instructions operable to receive thesignal and/or data over the wireless network and to effectuate a remotevisual and/or audible alarm for a remote helmsperson, skipper, and/orcrew member having that device.

In another embodiment, computer readable tangible media furthercomprises the remote data and remote instructions operable for theremote mobile device to receive the signal and/or data sent over thewireless network and effectuate the remote visual and/or audible alarm.

In a still further embodiment, there is computer readable tangible mediahaving data and instructions operable to be performed in a mobilecomputing device comprising the camera, tangible media operable to storethe data and instructions, a processor, a touch-sensitive displayscreen, a speaker, and a wireless network interface controller, where amobile computing device can be a smartphone, a tablet computing device,and/a portable computer.

This disclosure also describes a method of accumulating a sum ofincremental angles of windlass rotation to determine a length of rodetraversing a gypsy of a windlass in an anchoring operation based onreceiving a plurality of samples of a sound field in a directionalmicrophone fixed to the windlass, and storing a digital representationof each sound sample in tangible media. The method includes steps ofdetecting a pattern characteristic of a difference between a later andan early angular position of the windlass in the digital representationsof the samples, and extracting a signed incremental rotation angle ofthe windlass from the sound sample based on detecting the pattern. Thesigned incremental rotation angle is added to a sum of signedincremental rotation angles, and the sum is multiplied by a calibrationfactor defining a length of rode that is released proportionate to anangle of windlass rotation.

There is a further aspect of the directional microphone method thatincludes receiving a plurality of samples of a sound field in anomnidirectional microphone fixed to a central position of the windlass,and using the sound samples from the omnidirectional microphone tosuppress omnidirectional background sound and/or improve the patterndetection.

Another aspect of the disclosure is tangible media comprisinginstructions and data operable for a computer to perform the steps formeasuring a length of rode traversing a windlass gypsy and a rate ofrode being released and/or gathered by the windlass gypsy in ananchoring operation, including steps of receiving a plurality of samplesof a sound field with a directional microphone fixed on the windlass,and storing a digital representation of each directional microphonesound field sample in tangible media. The instructions and data arefurther operable to perform steps of detecting a pattern characteristicof a difference between a later and an early angular position of thewindlass in the digital representations of the plurality of sound fieldsamples from the directional microphone, and extracting a signedincremental rotation angle of the windlass based on the characteristicpattern detected. The instructions and data can also perform the stepsof adding the signed incremental rotation angle to a sum of signedincremental rotation angles, and multiplying the sum of the signedincremental rotation angles by a calibration factor defining a length ofrode that is released proportionate to an angle of windlass rotation.

Other tangible media comprises operable instructions and data for aprocessor to perform steps for capturing a plurality of digital imagesusing an image sensor, performing a computer vision algorithm operableto extract an amount and rate of angular rotation of a windlass from thedigital images, and determining a length and rate of rode release basedon the rate and the amount of angular rotation.

An aspect of the written description discloses tangible media comprisinganchoring data and instructions operable for a local mobile computingdevice to measure a real time rate and length of rode traversing awindlass, where the local mobile computing device includes a processor,tangible media operable to store data and instructions, a digital cameraoperable to capture digital images of the windlass in real time, atouch-sensitive display screen, a speaker, and a wireless networkcommunication interface. The anchoring data and instructions areoperable for the processor to determine real time information includinga length of rode release and a rate of rode release using the captureddigital images of the windlass to sense an amount of angular rotation.The anchoring data and instructions are further operable to communicatethe real time information from the local mobile computing device to aremote crew member by sending the real time information from the localmobile computing device over a wireless network to a remote mobilecomputing device. The remote crew member receives the information fromthe remote mobile computing device. In an embodiment, the mobile deviceis selected from among a smartphone, a tablet computing device, and aportable computer.

This disclosure describes means for using a computing device selectedfrom the group consisting of a smartphone comprising a digital cameraand a tablet computer comprising a digital camera to measure a length ofrode release from a windlass in real time, wherein the length of rodetraveling through the windlass is proportional to angular rotation ofthe windlass.

In a further aspect of the disclosure, there is an apparatus operablefor a crew member to use to measure a rate and length of chain lengthmoving through a windlass of a boat. The apparatus comprises a processorand a camera operable to capture sequential digital images of adistinguishable rotatable portion of the windlass wherein the sequentialimages include information operable for a processor to perform steps fordetermining an angular velocity of a portion of the windlass. Theapparatus also has a network interface controller and machine readabletangible media. The machine readable tangible media comprises data andinstructions operable for a processor to perform steps for determining areal time length of rode chain release and a real time rate of rodechain release, based on a sequence of digital video images selected fromthe group consisting of digital video images comprising an upper surfaceof a windless, and digital video images comprising a windlass gypsy andchain links emerging the windlass gypsy. The data and instructions arefurther operable to perform steps for determining a boat location andusing the boat location to find a real time speed of the boat anddistance of the boat from an anchoring site. The data and instructionsare operable to compare a value of the real time rate of the real timespeed of the boat to a value of the real time rode chain release andsend an alarm if the ratio of these values exceeds a predeterminedthreshold alarm value.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments are illustrated in an exemplary manner by theaccompanying drawings. The drawings and accompanying description shouldbe understood to explain principles of the embodiments rather than belimiting. Other embodiments will become apparent from the descriptionand the drawings:

FIG. 1 shows a boat anchored to a seabed.

FIG. 2 shows an anchored boat swing after anchor set.

FIG. 3 shows an image of a standard vertical WL and its main components.

FIG. 4 shows an image of a WL gypsy with anchor rode.

FIG. 5 shows a vertical WL mounted on a bow deck of a boat.

FIG. 6 shows a horizontal WL in storage cabinet of a boat.

FIG. 7 is a simplified diagram of rode and boat movements whenanchoring.

FIG. 8 shows a simplified flowchart illustrating user and applicationsteps of measuring a gypsy diameter using smartphone AR application.

FIG. 9 shows a display including virtual and real objects in a gypsydiameter measurement using smartphone AR applications.

FIG. 10 illustrates a manual gypsy diameter measurement.

FIG. 11 shows examples of typical WLC markings.

FIG. 12A shows simplified steps for measuring a rotation of a WL with amarking using a computer vision video frame analysis.

FIG. 12B shows a simplified flowchart for computing the angle of a WLrotation.

FIG. 13 is a simplified diagram showing an embodiment of a WL having asensor module.

FIG. 14 shows a simplified embodiment of WL modules having active and/orpassive conspicuity elements operable to facilitate computer vision.

FIG. 15A shows a simplified diagram of a frame operable to maintain acamera device in a preferred position relative to a WL.

FIG. 15B is a simplified diagram of an embodiment of a camera module forcapturing video images of a WL.

FIG. 16 shows top and side views of a WL module includingomnidirectional and directional microphones.

FIG. 17 shows a simplified flowchart of a method for measuringincremental rotation angles of a WL using audio signals from microphonesshown in FIG. 16.

FIG. 18A is a simplified view of a module including two 3-axial MEMSaccelerometers configured to sense an angular rotation of a WL.

FIG. 18B is a simplified view of a module having one 3-axial MEMSgyroscope configured to sense am angular rotation of a WL.

FIG. 18C is a simplified view of a module having one 3-axial eCompassconfigured to sense an angular rotation of a WL.

FIG. 19A shows an embodiment of an iPad screen image displaying recordedand computed WL rotation measurements.

FIG. 19B shows a screen image of an iPhone displaying WL rotationmeasurements and visual cues and alerts in an embodiment.

DETAILED DESCRIPTION

Novel methods and apparatus are disclosed that provide improved abilityto anchor a boat reliably and securely. In various embodiments, realtime values of the rate of rode release, and the length of rode that hasbeen cumulatively released are measured and/or monitored using variousmethods and simple low-cost equipment disclosed herein. The rate of roderelease and the cumulative length of rode released in combination withreal time values of boat velocity, trajectory, and rode status displayedenable crew members to perform safe anchoring.

In an aspect of this disclosure, methods and apparatus to determine thelength and rate of rode release depend on a series of real time videoimages of a WL captured with a digital camera. The angle of rotation andangular velocity of the WL are extracted in real time by machine visionalgorithms in a computer application program.

In another aspect, angular motion, e.g. an angle of rotation and/orangular velocity, of a WL is measured using sensors responsive to forcesand/or motion. In still further aspects, the rotation of a WL and thelength and rate at which anchor rode is being released are extractedfrom sound received by a microphone attached to a WL.

In still further aspects, a disclosed method depends on a machine visiontechnique known as optical flow analysis. This method can determine alength and/or rate of anchor rode release. In the method an optical flowanalysis of sequential images of the rode (rode image data) acquiredwith a digital camera does not require determining the WL rotation or WLrotation angle. Some embodiments of the method can be self-calibrating.However, a method of optical flow analysis can also include steps fordetermining a calibration relationship.

Parameters describing the rotation of a WL include the angular velocityof the WL, the rate at which rode traversing the gypsy of the WL isbeing released or gathered, and the cumulative algebraic total length ofrode that has traversed the gypsy during a selected interval of time.Various methods operable to determine values of these parameters aredisclosed. Generally, these methods depend on establishing apredetermined relationship (calibration factor) relating a length ofanchor rode (X) that has travelled through the gypsy of a WL to an angle(Ø) of WL rotation. In a number of embodiments, the calibration factorcan be found using augmented reality in a computer display userinterface. In some further embodiments, a calibration relationship canbe based on characteristic manufacturer's data in a database, and/orprior calibration(s) of the same WL and rode, or same type of WL androde, found in a database.

The terminology herein is for the purpose of describing particularembodiments and is not intended to be limiting of the disclosures. Itwill be understood that, although the terms first, second, etc. may beused to describe various elements, these terms are only used todistinguish one element from another, and the elements should not belimited by these terms. For example, a first element could be termed asecond element, and similarly a second element could be termed a firstelement, without departing from the scope of the instant description. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” “including,” and/or “having,” as used herein,are open-ended terms of art that signify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. Reference in the specification to “one embodiment”, “anembodiment”, or some embodiment, etc. means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. The appearances of the phrase“in one embodiment” in various places in the specification are notnecessarily all referring to the same embodiment, nor are separate oralternative embodiments mutually exclusive of other embodiments.

As used here, various terms denoting spatial position such as above,below, upper, lower, leftmost, rightmost and the like are to beunderstood in a relative sense. The various aspects of the apparatusesdescribed herein are operable without regard to the spatial orientationof the apparatuses as a whole. For example, an apparatus can beconfigured in a vertical orientation or in a horizontal orientation.Hence a component or module that is described as being above anothercomponent or module in a first embodiment having a first orientation,could equivalently be described as being to the left of the othercomponent or module in an equivalent second embodiment configured to bein a second orientation 90 degrees counterclockwise with respect to thefirst.

The term module refers to a distinct unit that is operable to perform anidentifiable function. A module can be a self-contained physical unit orpiece of equipment. A module can also be a logical component effectuatedby a processor and tangible media having instructions and/or data thatare operable for the processor to perform the identifiable function. Theterm automatic refers to a module, service, or control system that isoperable to perform without human interaction.

Angular position means the value of an angle, which in conjunction witha radius value, defines a location in a polar coordinate system. Acounterclockwise sense of angular rotation is understood to increase theangle (effectuate a positive change in angular position) and a clockwiseangular rotation to reduce the angle (effectuate a negative change inangular position), unless stated otherwise. An angle of rotation isincreased by 360 degrees (2π radians) for each full revolution in thepositive sense, or decreased by 360 degrees for each revolution in thenegative sense.

A WL refers to a mechanical assembly used to release or retractanchoring rode on a boat whereby an anchor can be set or withdrawn.Generally, a WL comprises a distinct generally circular uppermostportion termed a capstan. A WL also comprises a gypsy that engagesanchoring rode as it traverses the WL. Gypsy diameter (D_(G)) refers tothe linear distance along a diameter drawn from one midpoint where ataut rode is in contact with the gypsy through the center of WL gypsyrotation to an opposing midpoint where the rode is in contact with thegypsy. Effective D_(G) means the diameter providing the length of a rodetraversing a gypsy when multiplied by an angle of rotation Ø, where Ø ismeasured in radians (2π×degrees/360). Incremental WL rotation angle(ΔØ_(INCR)) refers to the difference in angle of a WL during the courseof rotation around its axis. Incremental rode length (ΔX_(INCR)) is thesigned quantity of rode traversing the gypsy calculated using D_(G) andΔØ measured during a measurement time interval Δt during the anchoringoperation, where ΔX_(INCR)=ΔØ*D_(G)/2. Total rode length X_(TOT) (at agiven point in time) is the total length of rode extending from the WLto the anchor location, and X_(TOT)=ΣΔX_(INCR). The rate of rode release(where ΔX_(INCR) is a positive number) or gathering (where ΔX_(INCR) isa negative number) is calculated as ΔX_(INCR)/Δt. The “boat distance”(from anchor location) is the horizontal linear distance between a pointwhere a line perpendicular to the set anchor intersects the watersurface and the bow of the boat at the waterline.

A windlass rotation angle will be understood to mean the angular amountof a windlass rotation around the center of the windlass with referenceto a concentric polar coordinate system.

A signed quantity will be understood to mean a quantity that can bepositive or negative. For example, a positive length of rode is a lengthof rode that has emerged from a windlass of a boat, usually going into abody of water. Rode is generally released (moved) by the gypsy of awindlass. A negative length of rode is a length of rode that is drawninto the windlass, usually gathered from a body of water.

A sum will be understood to mean an algebraic total formed by theaddition of individual amounts of a quantity where each of the amountscan be a positive or negative signed quantity. For example, whererotation can be in a positive or negative sense, a sum of incrementalangles of rotation means the algebraic total amount of rotation definedby an algebraic addition of positive incremental angles and negativeincremental angles to find an algebraic total angle of rotation.

The term computer will be understood to mean a processing system thatincludes a processor and tangible memory, wherein the memory is operableto store data and instructions, and the processor is operable to performthe instructions and operate on the data.

The term “tangible” as used herein, is intended to describe acomputer-readable storage medium (or “memory”) excluding propagatingelectromagnetic signals, but are not intended to otherwise limit thetype of physical computer-readable storage device that is encompassed bythe phrase computer-readable medium or memory. For instance, the terms“non-transitory computer readable medium” or “tangible memory” areintended to encompass types of storage devices that do not necessarilystore information permanently, including for example, random accessmemory (RAM). Program instructions and data stored on a tangiblecomputer-accessible storage medium in non-transitory form may further betransmitted by transmission media or signals such as electrical,electromagnetic, or digital signals, which may be conveyed via acommunication medium such as a network and/or a wireless link.

Augmented reality refers to a human-computer interface comprisingsuperposition of computer-generated image layers and an image of a realphysical object. The term digital camera refers to a camera that cancapture an image in a digital form (digital image). A digital videorefers to a periodic series of digital images (each image can bereferred to as a frame).

In a number of embodiments, various apparatus and methods are disclosedto measure angular movement of WL rotations and the rate of rodereleased and/or gathered by the WL gypsy based on imaging of the WLrotation. A system for imaging can include a digital image sensor (forexample the image sensor in a smartphone camera, or an electronic imagesensing array in a stand-alone camera) to capture the images of arotating WL during anchoring operation and a processor to analyze theseimages in real time to provide feedback to crew members of a boat.Augmented reality and computer vision algorithms can be used to enhancevarious aspects of these measurements as well as for the analysis ofsequential WL images in the following sections.

In a number of embodiments, various specialized software applicationsrunning on a computing mobile device receive the raw measurement data inthe form of video frames, audio signals and/or MEMS sensor data, applythe necessary computational algorithms and display the results to crewmembers. Such commercial mobile devices can include smartphones, tabletcomputers (“tablets”), portable personal computers, smartwatches, andsmart glasses. The current capabilities of smartphones and tablets aregenerally sufficient to capture audio-video frames, analyze video imagesand detect a distinguishable marking and/or repeated pattern therein,compute values of parameters that are essential for anchoring, anddisplay textual and graphical information such as rode release data, allin real time. Furthermore, many of these mobile devices include embeddedaccelerometers, gyroscopes, multiple cameras, multiple microphones, andmagnetometers that can be accessible via Application ProgrammingInterfaces (APIs). While there are smartwatches that include cameras,current smartwatch products are not suitable to analyze video framesusing Computer Vision (CV) algorithms in real time, owing to relativelylimited computational speed and memory. However, this situation maychange in the future as computation capabilities, miniaturization, andenergy efficiency evolve.

Generally marine vessels can be range from 6-meter recreational powerboats through 350-meter aircraft carriers and can be powered by nuclearpropulsion, internal combustion engines and/or wind. All marine vesselsrequire reliable and accurate methods for measuring rode length duringthe course of anchor operations. Some of these large commercial ormilitary marine vessels may employ mechanical and/or electromechanicalchain counters to measure the rode length. Regardless of the size ortypes of the marine vessels, all marine vessels will benefit from theanchoring methods disclosed herein.

Although most examples of anchoring devices and methods described hereinrelate to vertical windlasses having axes of rotation perpendicular tothe boat deck, the instant teachings are also effectuative forhorizontal windlasses.

In various embodiments, instant methods disclosed herein rely onmeasuring incremental WL rotation angles, ΔØ_(INCR), and WL gypsydiameter, D_(G), to compute rode length, ΔX_(INCR). Generally, gypsiesare sold by WL manufacturers matched to a specific WL and chain (orrope) combination complying with existing International and USAStandards for windlasses and chains. However, in some circumstancesmanufacturer data sheets or archival values for D_(G) may not be readilyavailable to a crew during anchoring. It is critical to have a practicaland convenient method of measuring an effective gypsy diameter of a WL.

A novel method of determining the length of anchor chain released orgathered depends on calibrating the length of chain release X traversingthe gypsy as a function of WL rotation angle Ø and monitoring theangular WL rotation during an anchoring operation. In some embodiments,specific WL dimensions and/or other characteristics, i.e. diameter of acapstan and/or gypsy, characteristic chain link dimensions, etc., can beaccessed from manufacturer data and used to calculate a minimum andmaximum chain length traversing the gypsy per WL rotation angle.Depending on the embodiment, this calculation can be useful for anactual, a trial and/or a rough calibration.

In various embodiments a correction is made when the camera is above theWL in a position from which the region where chain emerges from thegypsy is partly or wholly blocked by the capstan or structure. To refinethe calibration further, lengths of chain are released onto a flatsurface and measured (for example on a deck) while monitoring the angleof rotation and/or number of rotations of the WLC. The measured ratio ofthe length of chain released per amount of angular rotation can be usedas a calibration factor to improve accuracy.

A smartphone having a camera and/or tablet with a camera can be used tocalibrate chain release per WL rotation. The calibration can beperformed in the field with a user interface based using augmentedreality. A 3D camera can facilitate the calibration process. A number ofcommercial smart mobile phones and tablets have built-in 3D camerasand/or means to simulate a 3D camera. In some embodiments, a simulated3D camera depends on software processing images obtained throughintentional camera movement. The 3D camera can acquire an imagecomprising dimensions of the object to be measured and present imageinformation on a screen. In various embodiments a virtual image layercan comprise a set of points, a line, a circle, and others. A user canalign various elements of the virtual layer with the image of an objectthat is shown on the screen. In this manner a user can identify acharacteristic element of an object and effectuate a measurement of anelement dimension. More particularly, an effective diameter of a WLgypsy can be identified and measured. Once the effective diameter of theWL gypsy is thus measured with AR, a circumference and the length ofchain released/gathered per unit angular rotation of the WLC can becomputed.

FIG. 8 has a simplified flow chart of a method for measuring aneffective gypsy diameter using Augmented Reality (AR) in a mobile devicesuch as a smartphone. At step 805 a user starts an application for ARcalibration on a mobile device in FIG. 8, which initiates the executionof the AR application process at step 807. A user interface (UI) displayat step 810 can allow the user to choose a default digital camera or arear facing digital camera, depending upon the embodiment. Uponselecting the camera at step 815 as a user input (usr inpt), theapplication begins to acquire video frames from the camera at step 818.The WL 300 and chain 125 emerging from the WL seen on the screen ispreferably recorded in an orientation wherein the bottom and top of theimages in video frames correspond to the bow and stern of a boat (FIG.9). At step 820, the user can adjust the camera position and orientationto have the field of view (FOV) to enclose both the WL and the portionof the chain emerging from the WL as seen in FIG. 9. At step 823 in FIG.8 the application displays video frames having the WLC alignment target(AT) 905 superimposed on the WLC, as can be seen on the screen displayin FIG. 9. At step 825 the user can use gestures operable to resize andcenter the AT 905 over the image of the WLC in the video frames. At step830 the user verifies if the AT is centered 910 over the WLC image asshown by FIG. 9. At step 833 the application can scale and move the ATon the image of the WLC in response to finger gestures, project the ATon the WLC position virtual (VR) 3D space. Upon the user's touch on acapture widget at step 835, the application saves the AT projected 3D VRcoordinates, and generates and displays a virtual chain alignment keyline (CAK) 915, extending upward from the horizontal diameter targetline 912 shown in FIG. 9, at step 838 in FIG. 8. At step 840, the usercan use gestures to extend and move the CAK 915 on the display. At step845, the user verifies the CAK centered over a midline of the chainemerging from the WL. In step 843 responsively, the application codeextends the CAK length and moves the CAK 915 horizontally per usergestures, and projects CAK to the chain/WLC position in VR 3D space,calculates the distance between the AT center 910 and the CAK base 917,and then computes and displays the effective gypsy diameter D_(G). Atstep 845 the user verifies the CAK centered over the emerging chain fromthe WL. At step 850 the user touches a widget. Upon receiving user inputat step 850, the application saves the effective gypsy diameter D_(G) ina device database (dB) record and optionally schedule to upload (UL) tocloud dB at step 853. At step 855 the calibration process ends. Once theAT and CAK VR 3D space coordinates are determined, the subsequentcalibration process is relatively independent of the camera motionsrelating to the changing user and/or camera position. The effectiveD_(G) obtained from this calibration process can be used by crew membersduring anchoring operation in various embodiments.

Alternatively, an effective gypsy diameter D_(G) can be measuredmanually. A crew member measures the outer diameter of the WLC (D_(C))1005 using a tape measure and/or ruler in FIG. 10. A ruler depicting astraight edge line 1010 in FIG. 10 is placed tangentially to the outeredge of the WLC near the chain 125 emerging from the WL. The ruler isheld parallel to the length of the chain emerging from the WL. Anotherruler represented by line 1015 in FIG. 10 is centered along the chainemerging from the WL. The distance between the line 1010 and 1015 (r_(d)1020) is measured using a tape measure and/or ruler. D_(G) is computedfrom D_(G)=D_(C)−(2*r_(d)).

The system measuring the angular rotation of a WL includes a digitalimage sensor, a processor to read and perform computations from serialimages of a WL rotation recorded, a machine-readable tangible media tostore data and algorithms, and human readable interface. The imagesensor can be a smartphone camera, a portable or a dedicated camera.

In some embodiments, angular rotation of a WL can be measured bycapturing images of the WL using a digital camera, and sensing changesin the angular position of a characteristic feature on the WLC with acomputer vision algorithm. FIG. 11 shows examples of common windlassesused for anchoring boats less than about 72 feet long, and somecharacteristic intrinsic distinguishing markings and features on theircapstans. A manufacturer's logo 1100 and/or other localized graphicalfeatures 1105, 1110, 1115, 1120, and 1125 are conspicuous. The positionof the logo “Quick” 1100 on the WLC can be sensed and used to compute anangular movement and/or velocity of WL rotation.

In further embodiments, a surface imperfection imprinted during courseof manufacturing of a WL, or a blemish, originating from wear during use(see features 1130 and 1135 in FIG. 11) can be used to monitor angularmotion of a WL. A useful surface blemish/imperfection can be identifiedusing a computer vision algorithm such as digital image correlation andtracking (DIC), and/or artificial intelligence techniques (see, forexample, “Digital Image Correlation and Tracking” retrieved fromhttps://en.wikipedia.org/wiki/Digital_image_correlation_and_tracking onMar. 23, 2020 and references 1-11 therein; Low-contrast surfaceinspection of mura defects in liquid crystal displays using opticalflow-based motion analysis, by Du-Ming Tsai et al. in Vol. 22, No. 4,Machine Vision and Applications, July 2011; Jong-Seung Park, Seung-HoLee, “Automatic Mura Detection for Display Film Using Mark Filtering inWavelet Transformation”, IEICE Transactions on Information and Systems,Vol. E98-D, No. 3, pp. 737-740, March 2015; Machine Vision-BasedConcrete Surface Quality Assessment. Journal of Construction Engineeringand Management, by Zhu, Z. and Brilakis, I. 136(2), 210-218, 2010; allof which are hereby incorporated by reference in their entirety).

Absent a conspicuous intrinsic position marking (e.g. local texturefeatures, local structural features, local areas having alpha numericcharacters, and others) on the WLC, a high contrast trackable featurecan be added to a visible upper surface of the WL. For example, adistinguishable trackable feature can be applied to the surface of theWLC with a bonding agent, and/or ink or paint marking(s) such as a line,geometric shape, or pattern and/or a suitable colorful tracking featureto facilitate algorithmic feature recognition. In an embodiment,commonly available black electrical tape can also be used as a positionmarking. FIG. 11 shows a WL with a piece of black tape added 1140 toprovide a position marking for monitoring the WLC rotation. In view ofthe instant disclosure, it will be apparent to those having ordinaryskill in the art that a conspicuous scratch on the surface of thecapstan, a manufacturer's stamping, or similar can be used a marking forthe computer vision algorithm to track the motion of the WL. A digitalcamera can be disposed in a position providing a full view of the markeduppermost surface of a capstan (e.g. generally above a vertical capstanand laterally with respect to a horizontal WLC).

FIG. 12A shows a simplified flow chart of a method for measuring anincremental WL rotation angle and rode length in real time. The methodincludes capturing video frames of a distinguishable marking on arotating WLC, detecting the marking on the moving WLC using ComputerVision algorithms, and tracking frame to frame movement of the markingto determine the amount and/or rate of the WL angular rotation and alength of rode corresponding to the rotation angle. The method canmeasure both instant and cumulative amounts of rotation and/or releasedlength of rode.

One aspect of this method includes finding a circular boundary definingthe outermost edge of the WL in each video frame. In variousembodiments, the circular boundary can be identified using aconventional computer algorithm for detecting a circular boundary inimages. A guide circle, “WL Guide” 1217 in FIG. 12A, can be drawn on thedisplay of a digital camera. By this way, a user can adjust the positionand orientation of the camera to capture the image of the WL in similarsize and extent to WL Guide 1217. At step 1200 in FIG. 12A, the camerabegins to acquire video frames comprising the WLC with a distinguishablemarking. At step 1205 detection threshold parameters are set to identifycandidate WL circles. Initial threshold is predetermined based on size,contrast and/or others. In some embodiments, threshold can be adjustedusing a heuristic based on history. At step 1210 the Hough Circlealgorithm and/or similar circle detection algorithms can detect allcircles in the frame(https://docs.opencv.org/master/da/d53/tutorial_py_houghcircles.html,https://livecodestream.dev/post/hough-transformation/,https://en.wikipedia.org/wiki/Circle_Hough_Transform, all retrieved onMar. 28, 2021, all of which are hereby incorporated in their entirety).At step 1215, the algorithm looks for one circle that is exclusivelyabove the detection threshold. At step 1220 the circle meeting thethreshold criteria is selected as “WL circle”. At step 1223 detection ofthe WL circle is notified to the user by displaying WL Guide in yellow.If the WL circle detection fails in the frame being analyzed, thealgorithm acquires next video frame and the steps of the WL circledetection is repeated as described above.

Another aspect of the method includes detecting a distinguishablemarking on a WLC and finding polar coordinates of the marking relativeto the center of the WL. The marking on the WLC can be identified usingvarious image analysis algorithms which will be known to those havingordinary skill in the art. In an embodiment, everything outside of theWL circle in the frame is removed at step 1125 and an image 1226 in FIG.12A. At step 1230 the contents of the WL circle can be converted toinverted greyscale computationally (see 1231 and 1236 in FIG. 12A) using“erode, dilate and bitwise invert” transformation programs(https://docs.opencv.org/3.4/db/df6/tutorial_erosion_dilatation.html,retrieved on Mar. 28, 2021, all of which are hereby incorporated in itsentirety). At step 1235 the algorithm, “findContour” can be used todetect all contours (features or white blobs) within the WL circle imageand assigns each blob a center and radius(https://docs.opencv.org/3.4/d3/dc0/group_imgproc_shape.html,https://docs.opencv.org/master/d9/d8b/tutorial_py_contours_hierarchy.html,retrieved on Mar. 28, 2021, all of which are hereby incorporated intheir entirety). A blob refers a distinguishable feature and/markingwith a flat plate of uniform mass. At step 1240, the algorithm analysesall white blobs by size and selects the largest blob (or marking). Atstep 1243 the detection of the marking on the WLC is notified to theuser by displaying the WL guide in green.

Further aspects of the method include detecting the rotation of WL usingthe marking on the WLC and computing the incremental WL rotation angle,ΔØ_(INCR), and rode length released by the WL rotation, ΔX_(INCR). Atstep 1245 the polar coordinates of the blob in the frame are obtainedand saved in memory of the local device and/or uploaded to a server. Atstep 1250 an angular coordinate of the blob (Ø) in an instant frame j(Ø_(j)) is compared to its value in the previous frame i (Ø_(i)). If thedifference (ΔØ_(ij)=Ø_(j)−Ø_(i)) exceeds a predetermined threshold (Th)at step 1255, the detection of WL rotation is notified to the user bydisplaying “WL Rotation Detected” at step 1258. An incremental WLrotation angle ΔØ_(INCR) and incremental rode length ΔX_(INCR) arecomputed at step 1260.

FIG. 12B is a simplified flowchart showing computation of an incrementaland total WL rotation angle (ΔØ_(INCR) and ΔØ_(TOT)) from WL videoframes acquired. The initial blob coordinates (Ø_(i) and Ø_(j)) aredetermined before the beginning of the routine. At step 1270 index i andj, and ΔØ_(TOT) are initialized at step 1270. The algorithm gets frame jat step 1273 and detects the blob coordinates at step 1276. If the frameis invalid, j is incremented by one at step 1288 and subsequent frame isacquired. If the frame is valid at step 1279, the change in WL rotationangle between frame j and frame i (ΔØ_(ij)) is calculated at step 1282.If ΔØ_(ij) does not exceed a predetermined threshold value (ΔØ_(Th)) atstep 1285, j is incremented by one at step 1288 and next frame isobtained for analysis. If ΔØ_(ij) is greater than the threshold value atstep 1285, the total WL rotation angle, ΔØ_(TOT), is calculated byadding the previous value of ΔØ_(TOT) to ΔØ_(ij) at step 1291. The indexj, Ø_(j) are set as i and Ø_(i) respectively at step 1294. The index jis incremented by one at step 1288 and analysis continues withsubsequent frames recorded during an anchoring operation as describedabove.

The computer vision algorithms used for the measurement of WL angularrotation disclosed herein include stringent error correction codes forhandling incorrectly identified circles and/or blobs, as well motioncorrection during the course of measurements.

In further embodiments, features on the WLC and/or WL associated modulescan be identified using standard CV color identification algorithms(Boosting Color Saliency in Image Feature Detection, J. van de Weijer,Th. Gevers, A. D. Bagdanov, IEEE Transactions on Pattern Analysis andMachine Intelligence, Jul. 30, 2005, all of which are herebyincorporated in its entirety).

A method of using another machine vision algorithm known as optical flowanalysis to determine the proportional calibration factor relatinglength of chain released to WL rotation angle was discovered. Opticalflow analysis algorithms generally perform a frame by frame analysis ofa video sequence in which an object (or a set of objects) moves in aconsistent direction of motion with respect to an observer (the field ofview of an image sensor). The term optical “flow analysis” originatedfrom its use to estimate a velocity of fluid flow in a channel. Opticalflow analysis algorithms are disclosed in the prior art article “OpticalFlow” retrieved from https://en.wikipedia.org/wiki/Optical flow Mar. 24,2020 and references 1-20 therein, all of which are hereby incorporatedby reference in their entirety.

According to the present method, links in a rode chain being released orgathered to/from the edge of the boat, pass through the field of view ofa digital camera. Instructions operable to perform an optical flowanalysis algorithm with a computer are used to analyze frame by framechanges of contrast arising from areas of the chain in the digitalimages. As chain links move through the digital camera field of view,each frame is analyzed in relation to previously recorded frame(s) todetect the number of chain links passing through the field of view.Furthermore, based on changes in a gradient of serial images during thecourse of motion, both the direction and variations in “flow” can befound. By this method, a length of chain release is measured as the WLrotates through a determined angle.

In a further aspect, there is a method of monitoring the velocity andamount of rode release without monitoring WL rotation. According to thismethod, chain release and/or gathering during an anchoring operation ismonitored using a digital camera to acquire a video comprisingsequential digital image frames of the rode chain motion during ananchoring operation (rather than images of WL motion), and determiningthe velocity and amount of chain release by applying an optical flowanalysis algorithm to these digital images of the moving chain.

Chain length measurements obtained using optical flow analysis canrequire calibration, depending on the embodiment. Variability in theangle and distance of the camera with respect to the chain link emergingfrom the WL gypsy can introduce errors. Corrections can be made byadjusting the optical flow measurements of chain release based on adirect measurement such as a physical measurement of a length of chainreleased and/or chain link dimensions, that can be performed duringmeasuring process. Alternatively, characteristic chain link and/or chainlength data retrieved from a manufacturer's data base can be useful tomake such corrections. It will be further understood that thereliability and accuracy of measuring chain length using optical flowanalysis can be further improved by comparing the acquired data andresults to measured values of parameters for a specific chain obtainedfrom a database and/or through site human interaction (directmeasurement with a physical standard and/or another measuring device).

In various embodiments, the imaging data acquired during anchoringoperations can vary depending on lighting conditions, the angle of view,and the settings of a digital camera. The data collected during variousanchoring conditions and a library of a commercial WL images can beanalyzed further using image processing techniques and statisticalmethodology to reduce variability and improve the accuracy and/orreliability of the measurements. Accuracy and reliability of varioussteps of the disclosed methods such as the detection of characteristicmarkings and/or trackable features on the WLC can be further improved bytraining and testing machine vision and/or artificial intelligencealgorithms with these large datasets. A necessary and sufficient lengthof rode required for secure anchoring can be is estimateddeterministically using computed incremental WL rotation angle and acalibration factor described above. By this way, both the accuracyand/or reliability of WL angular rotation measurements and the machinevision and/or artificial intelligence algorithms can be improvedcontinuously.

As a matter of convention, WL manufacturers provide a winch handlesocket configured as an 8-pointed star with a perimeter consisting ofthe exterior segments of two concentric identical squares with 17.4625cm sides, turned 45° with respect to one another as depicted in FIG. 13.Nearly all windlasses have a winch socket located at the center of theircapstans so that the motor clutch can be disengaged. FIG. 13 issimplified diagram of an embodiment of a WL 300 module 1300 that can beeasily inserted into a winch socket 315 and affixed to the WL before ananchoring operation, then removed after its completion. WL module 1300includes a processor, memory, a standard wireless communication module(e.g. WiFi, Bluetooth, Zigbee, and/or others), and other components. Themodule 1300 can have a battery, a power distribution system, and aconnector interface for charging the battery.

A baseplate 1303 of the WL module 1300 can be attached to a keyshaft1305 extending downward from the baseplate. The keyshaft 1305 has ashape that is operable to securely attached to and maintain a fixedangular position relative to the WL. In various embodiments the keyshaftextends in a perpendicular direction from the baseplate. In onepreferred embodiment, the keyshaft 1305 can have a star-shapedcross-section that is operable to securely fit into and be held by astandard WL socket 315 (see FIG. 13 and Section A-A in FIG. 14). Astandard WL has a socket in the shape of a star-shaped concaveequilateral isogonal hexadecagon. The keyshaft can be a right cylinderwith the cross-sectional shape of the standard WL socket dimensionsslightly reduced so as to securely fit inside (for example thedimensions of the keyshaft can be about 99.5% of the WL socket. Infurther embodiments, a keyshaft cross section can scaled to 95% to 99%of a standard WL socket cross section, although a slightly smallerfactor may be operable, depending on the embodiment.

In some embodiments, the shape of the keyshaft 1305 can also be a squareto fit one of two squares forming the 8-pointed star shape of the winchsocket described above. Hence manufacturing of a square keyshaft can beeasier.

The WL module 1300 can have a removable cover 1420 which can be made ofa dielectric such as a plastic that is relatively transparent towireless transmission signals used for bluetooth, wifi, or the like,depending on the embodiment. The cover protects the electronic circuitsfrom various environmental factors such as bright sunlight and seawater.

In some embodiments, the WL module can include high contrast, active(powered) and/or passive conspicuous markings and/or object on a WLCand/or WL module to facilitate machine vision detection of a marking.For example, a circular pattern is detected without difficulty by aComputer Vision CV blob recognition algorithm.

FIG. 14 shows a simplified diagram of a WL module 1400 having active andpassive conspicuous markings. In some embodiments, the WL moduleincludes a high contrast active marking such as a light emitting diode(LED) 1405 on a printed circuit board (PCB) 1415 near the periphery ofthe WL module 1400. LED 1405 enhances the visibility of the module,particularly in the dark. The circular PCB 1415 of the WL module 1400 ismounted to a baseplate 1303 having a downward extending keyshaft 1305 asdescribed above. A removable cover 1420 protects all support electronicsincluding battery mounted on the PCB. In another embodiment, the WLmodule 1400 can include a passive marking such as a circular object 1410affixed to the surface of the removable cover 1420. The circular object1410 can be used alone and/or in combination with an LED to facilitate aCV blob algorithm to detect and track the rotation of a WL.

In some embodiments a crewmember can hold a camera in an elevatedposition selected to provide an unobstructed view of the top of a WLthat is used to release and/or gather chain during an anchoringoperation. In alternative embodiments, a camera can be held in anelevated position above the WL using a support module that can beattached to the deck or alternative part of the boat. A support modulecan provide improved stability and can be used to maintain the camera ina predetermined position relative to WL and/or the boat.

Maintaining a camera in a steady position manually by a crew memberduring the course of an anchoring operation can be challenging. Someexamples of these challenges can include significant motion at the bowof a boat to due to wind and waves, distractions of the crew memberrecording the WL rotation by various reasons, and/or the movement ofother multiple crew members near or around the area where the recordingtakes places. In a preferred embodiment, a digital camera 1500 isattached to a framework which is near the WL 300 at the bow of a boat1503 to capture the full view of a WLC during anchoring shown in FIG.15A. The camera 1500 can be mounted on a conventional “selfie stick”1505 and/or other commercially available cell phone or camera mountinghardware such as an iPad/iPhone holder, a conventional tripod ball headmount, a webcam stand mount, and/or others. The framework includes anumber of stanchions 1510, a number of metal lifeline cables 1515, aselfie stick 1505 or a single pole camera tripod having a module to afix a camera securely. The stanchions 1510 are standard features ofboats consisting of vertical chrome poles permanently mounted at evenlyspaced intervals along the sides (port and starboard) of a boat andextended around its front (bow) and rear (stern). The metal cable 1515is suspended between stanchions for the purpose of providing a “fence”to keep objects and crew members on the boat. A selfie stick 1505 orsingle pole camera tripod can be clamped to a stanchion nearest the WL300. The selfie stick 1505 or the pole extends a distance from thestanchion to the WL. A module which affixes a camera device such as asmartphone and others can be mounted at the end of the pole. In analternative embodiment, a camera tripod or camera mount with one or moresuction cups can be used to affix the camera to a suitable position on aboat to acquire the full view video images of a WL.

In other embodiments, the camera can be mounted on a motorized pan tilttripod mount, a motorized 3-axis gimbal stabilizer, a motorizedtelescope tracker, and/or a motorized stage or other support that can bemoved to a selected position in a plane (x-y motion) or in spaced (x-y-zmotion). Variously, depending on the embodiment, motors can configurethe position of a camera. For example, motors such as stepping motors,analog servo motors and/or others can be used to movably tilt the camerato a selectable angle, and/or can translate the camera to a positionoperable to record a suitable view of the top surface of a WL. A cameraangle and/or position can be effectuated using an electrical controlmodule such as a joystick-style control module configured to allow anoperator to adjust a camera mounting platform that is operable toprovide rotation on two perpendicular axes, and/or translation in two orthree perpendicular directions. The rotation can be limited or can befull 360-degree around one or both axes. The human interface for thecontrol can be electromechanical comprising electrical switches,potentiometers, encoding disks, and/or joysticks, or equivalents.Alternatively, some or all portions of the human control interface canbe effectuated using computer instructions that interact with anoperator through input/output devices such as a touchscreen display, amouse, buttons, and the like.

In various embodiments, the angle and/or position of the camera can beselected and/or maintained using a control loop. There are alsoembodiments where an angle and/or position of the camera isautomatically effectuated programmatically based on computer vision withlittle or no human interaction. There are also embodiments where humaninteraction is provided to a computerized system to determine a “hybrid”positioning of the camera. The angle and positioning of the camera ismaintained by a control loop in a number of embodiments.

In various embodiments, a smartphone device or a dedicated camera isused as a video frame capture device depending on the convenience of acrew member. The crew member installs a software application operable toperform various functions described in FIG. 12A and FIG. 12B to asmartphone and/or mobile computing device. The application captures theframes, performs the frame by frame analysis using available CVlibraries, computes incremental WL rotation angle ΔØ_(INCR), incrementalrode released ΔX_(INCR), total rotation angle ΔØ_(TOT), total rodelength ΔX_(TOT), and displays them to the users. In some embodiments, adedicated camera device with a wireless networking capability can beused to capture frames. The frames can be transmitted to other computingdevices over a network where CV algorithms can be run to computeincremental WL rotation angle ΔØ_(INCR), incremental rode releasedΔX_(INCR), total rotation angle ΔØ_(TOT), total rode length ΔX_(TOT) andfurther parameters.

An example of such a dedicated camera module 1540 is illustrated in FIG.15B. The module 1540 includes a digital camera 1500 mounted to a glassplate 1565 which is tightly sealed on an opening (or window) of asupportive baseplate 1550. The lens assembly of the camera 1500 isoriented toward the glass plate 1565. Camera 1500 is attached to PCBs1560 mounted on the baseplate 1550 as shown in FIG. 15B. To keepelectronic components of the module dry, the module is enclosed with aremovable cover 1555 sealed to the baseplate 1550. All supportelectronics including microphone, amplifier, audio-video encoding,microprocessor, memory, wireless communications, battery, batterysupport, GNSS electronics, and others can be attached to PCBs 1560.Threaded holes 1570 on the edge of the baseplate 1550 can be designed toconform to the standard ¼″ 20 threads per inch and/or various otherstandards used for tripods, “selfie sticks” and other camera mountingdevices. Conspicuous coloration of the cover 1555 and air cavity in theseal can help personnel find the module easily if it falls in the water.

A WL module having a plurality of microphones to sense sound in thevicinity of a WL can be used to detect a WL rotation angle. FIG. 16shows a simplified diagram of a WL module 1600 using directional andomnidirectional sound sensing to detect motion of a rotating WL. Adirectional microphone 1610 having relatively higher sensitivity tosound coming in from directions facing the microphone can be mounted ator proximate to the periphery of the WL to selectively detect soundarriving from a radial direction. A omnidirectional microphone 1605 canbe mounted at or near the center of the WL. In the embodiment shown inFIG. 16, microphones are on a PCB 1415 that can be attached to awindlass. The microphone frequency response can have a range ofapproximately 8 Hz to 20 kHz, although other ranges are operable,depending on the embodiment. The PCB can be mounted on a circularbaseplate 1303 and can include all necessary circuitry, supportingcomponents, and a power source. A keyshaft 1305 such as described withrespect to FIG. 13 can extend downward from the baseplate 1303 tosecurely attach to the WL in a fixed position. There can be a removablecover 1420 to protect the module from bright sunlight and sea water.

In an embodiment, FIG. 17 shows a simplified flow chart of detectingΔØ_(INCR) based on signals from the microphones of the WL module 1600described above. At step 1700 and 1703, signals from a directionalmicrophone A_(D), and omnidirectional microphone A_(O) are acquired asthe WL module 1600 rotates synchronously with a WL. At steps 1705 and1708 the signal from each microphone is digitized at a suitable samplerate f_(s) sufficient to resolve WL rotation. For example, a samplingrate of 8192 Hz for each microphone which can resolve an upper of 4096Hz audio frequency (Nyquist frequency) is useful in practice to recordWL rotation. At step 1710 and 1713 the signals from each microphone arenormalized and scaled, based on calibration data gathered prior toanchoring operation. Each digital signal is multiplied by a scale factorto correct for gain differences, if any, between the two microphones andassociated amplifiers. At steps 1715 and 1718 each signal is transformedinto the frequency domain using Fast Fourier Transform (FFT). At step1720 and 1723, each sample is binned using a suitable frequency intervalat Δf_(s). In one preferred embodiment, the Δf_(s) can be 32 Hz. Ingeneral, a binning frequency interval between about 20 and 100 Hz hasbeen found to be useful, depending on the dynamic range of themicrophone and audio analog to digital converter combination. (FastFourier transforms, binning, normalization and various other DigitalSignal Processing [DSP] operations are described in Digital Audio SignalProcessing, Udo Zolger, 2008, John Wiley and Sons, all of which isincorporated by reference in its entirety for all purposes). In variousembodiments, a corrected spectrum in which ambient sounds and noisereceived by the directional microphone are reduced and/or removed isformed by subtracting the normalized spectrum of audio from theomnidirectional microphone at step 1725.

However, there are further embodiments, where steps 1700 through 1725are performed in a different manner. For example, ambient sounds andnoise received by a directional microphone can be reduced and/or removedby subtracting normalized analog audio signals from one or moreomnidirectional microphones using analog circuitry. In some furtherembodiments, respective directional and omnidirectional microphonesignals are digitally sampled and normalized before subtracting therespective time domain samples (prior to performing any Fouriertransformation).

WL rotation speed can vary from 0 sec⁻¹ to as 10 sec⁻¹. The number ofsamples collected and maintained is generally greater than the numberrepresenting 1 full rotation of the WL because of the high variabilityof the WL rotation speed. The number of samples corresponding to atleast 2-3 rotations is found to be appropriate to ascertain to extract aWL rotational pattern. Hence, it is preferred to acquire higher numberof samples and decimate the signals instead of dynamically changing thesample rate.

Where an audio sampling rate performed is excessive relative to the rateof WL rotation, the difference spectrum can be ‘decimated’ using acommon DSP method to reduce apparent sampling frequency at step 1730. Ina number of applications, a sampling frequency less than 1/10 of theinherent time necessary for a WL to rotate 1 degree is excessive.Decimation can be performed by repeatedly accumulating and averaging aselected number of sequential spectra to filter out spurious background.For example, a sampling rate of 8192 sec⁻¹ used by some audioacquisition software/hardware means is much higher than necessary forsampling conventional WL rotation. Spectra obtained from performing anFFT of the 8192 sample/sec data stream can be decimated by averagingeach consecutive group of 256 spectra which corresponds to an effectivesample of 32 Hz. The resulting spectrum is added as a row to an N×256×1matrix, wherein N is the number of samples computed every 31.25 ms, 256is the number of frequency bins and 1 is the timestamp at which thesample was recorded. Actual number of samples that get averaged andstored in the matrix varies depending on the WL rotation speed duringanchoring.

A standard Artificial Intelligence (AI) technique or a deep learningmethod can be applied to the timestamped spectrum data to detectperiodic repetitive patterns associated with full rotations of the WL.At step 1735 a Long Short-Term Memory neural network can be applied tothe matrix to detect an audio patterns from a rotating WL in anembodiment (Deep Learning for Time Series Forecasting, Predict theFuture with MLPs, CNNs and LSTMs in Python, Jason Brownlee,https://machinelearningmastery.com/deep-learning-for-time-series-forecasting/,retrieved on Mar. 23, 2021, all of which are hereby incorporated byreference in its entirety). At step 1740 the WL rotation rate isextracted using time stamps. At step 1745 an incremental WL rotationangle, ΔØ_(INCR), can be computed from the time variant patterns.

Many smartphones and tablets comprise embedded DSP and AI softwarelibraries and their computational capabilities are sufficient to performthe various functions and/or operations described herein. The signal tonoise ratio when detecting of a WL rotation angle can be optimized bymodifying sample rates, FFT bin count, decimation, and/or integratingmethod with an AI technique to discern the time patterns in the timevarying FFT spectrum depending on the embodiment. Where there is a noisysignal, sound fields from a plurality of directional microphones can beuseful to extract characteristic patterns operable to detect andquantify WL rotation.

In some embodiments, various micromechanical sensing modules can be usedto measure angular motion of the WL rotation. A motion sensing modulecan include a micro-electromechanical sensor such asmicroelectromechanical system (MEMS) gyroscope, a MEMS accelerometer, astrain gage; and/or a magnetometer, a processor, a memory, a powersource, a device enabling wireless communications. The motion sensingmodule can be protected by a waterproof plastic enclosure and attachedto a WLC using an adhesive (tape or glue), or can be mechanicallyattached by a threaded hole and screw. As the WL rotates, the motionsensing WL module senses the amount, direction and velocity of theangular rotation of the WL. The processor in the sensor module receivesthe data from the module, stores the data in a memory, and transmits itto a computing device in a wireless network communication protocollayer. In some embodiments, a portion of the data transmission to/fromthe module can be encrypted. A software application in the computingdevice can determine the angular rotation of the WL and the cumulativelength of rode traveled through the gypsy based on data received fromthe sensor module.

A 3D accelerometer is a sensor that measures changes in velocity alongthree axes in a cartesian coordinate space. A single 3D accelerometercannot reliably measure WL rotation angle, however two 3D accelerometerslocated at different positions relative to the WL center can be used tomeasure WL rotation. FIG. 18A is a simplified diagram of a WL module1800 having two MEMS accelerometers 1805 mounted on a PCB 1415. Theaccelerometers can be at different radial coordinates measured from theaxis of WL rotation. The module 1800 can have a keyshaft 1305 extendingdownward from a supporting baseplate 1303 as described with respect toFIG. 13. A removable cover 1420 enclosing the WL module 1800 can be madeof a dielectric such as a plastic that is relatively transparent towireless transmission signals used for bluetooth, wifi, or the likedepending on the embodiment. The differences in tangential accelerationcan be used to compute incremental changes in WL rotation angle,ΔØ_(INCR).

Rotational motion using an accelerometer can be determined as describedin U.S. Pat. No. 8,352,210 (Mark J. Kranz, 2013, Multiple accelerometerapparatus for counting rotations of an object, and method of use, U.S.Pat. No. 8,352,210, filed Jul. 23, 2010 and issued Jan. 8, 2013) andother studies (Placement of Accelerometers for High Sensing Resolutionin Micromanipulation, W. T. Latt, U-X. Tan, C. N. Riviere, and W. T.Ang, Sens Actuators A Phy, 2011; EcoIMU: A Dual Triaxial-AccelerometerInertial Measurement Unit for Wearable Applications, Yi-Lung Tsai,Ting-Ting Tu, Hyeoungho Bae, Pai H. Chou, 2010, International Conferenceon Body Sensor Networks, which are hereby incorporated by reference intheir entirety).

In some embodiments, accelerometers 1805 can be mounted on a circularPCB 1415 at different radial distances from the center of the WLrotation. The “yaw” rotation around an axis perpendicular to a plane ofthe WL rotation, can be derived from the measured accelerations and thedifference between the radial distances (difference in radialcoordinates between the accelerometers) as described in the publication“Using Two Tri-Axis Accelerometers for Rotational Measurements”Application Note AN 019, Kionix, Inc. July 2015 (retrieved fromhttps://d10bqar0tuhard.cloudfront.net/en/document/AN019-Using-Two-Tri-Axis-Accelerometers-for-Rotational-Measurements.pdfon Mar. 1, 2021). The radial components of accelerations a₁, a₂ of theaccelerometers at distinct radial positions r₁, r₂, from the center ofthe rotating WL are given by:a _(r1)=ω² r ₁ and a _(r2)=ω² r ₂  EQ. 5where ω is the angular velocity of the WL. The angular velocity of theWL, ω, can be obtained from these respective radial accelerations andthe difference between radial distances:|ω|=√(|a _(r1) −a _(r2)|)/√D _(r)  EQ. 6where D_(r) is absolute value of the difference in radial distance|r1−r2| between the accelerometers. Those having ordinary skill in theart will recognize that D_(r) can be measured and/or refined by astandard calibration procedure. The accelerometers have an angularcomponent of acceleration (acceleration in the circumferential directionof the WL rotation) given by:a _(ϕ1) =r ₁ dω/dt a _(ϕ2) =r ₂ dω/dt  EQ. 7where a_(ϕ2), a_(ϕ1) are the tangential accelerations sensed by each ofthe respective accelerometers and the angular acceleration. Therelationships in EQ. 6 only provide a magnitude of angular rotation.Additional information defining the sense (direction) of rotation isnecessary to calculate the algebraic total length of rode release. Thedirection of rotation can be extracted from sensing the circumferentialforce which provides the tangential accelerations in shown in EQ. 7. Theaccelerations comprise the time dependent changes in angular velocitywhich collectively determine the direction of WL rotation at any giventime.

EQ. 6 by itself can be useful to reject measurements that fall below aselected threshold value where there is a likelihood of excessive noise,insufficient accuracy or other sources of unreliability. Similarly, anexceptional aberration in angular acceleration (EQ. 7) can be useful toreject a short-lived fluctuation. In practice, an accurate total lengthof rode release can be calculated using EQs 6 and 7 to accumulate thealgebraic total rotation of the WL over the time intervals betweenretained measurements (after discarding measurements that were rejectedbecause of falling below a minimum angular velocity parameter, or othercriteria.

Gyroscopes can be useful to measure motion such as rotation. MiniatureMEMS gyroscopes are generally embedded in smartphones, smartwatches, andtablets. Recent advances in the MEMS technology can provide low drift,<0.2°/h, high thermal stability and high resolution. MEMS gyroscopesmodules having specified limits of precision and drift are commerciallyavailable. Many of these modules have an embedded microcontrolleroperable to transmit and receive data using a standard bus communicationprotocol. For example, a number of MEMS gyroscope modules can send dataover the Inter-Integrated Circuit (I²C) bus. MEMS accelerometers,magnetometers, and eCompasses also include an I²C bus or similarwireless communication protocol to transmit and receive data.

A so called 3D gyroscope can measure angular velocity around three axesrelative to the force of gravity: X-“roll”, Y-“pitch” and Z-“yaw”.Changes in pitch or yaw, respectively, are transmitted over a wirelessnetwork to other devices that compute incremental changes in WL rotationangle, ΔØ_(INCR).

In further embodiments, a multi-axis MEMS gyroscope can be used tomeasure “yaw” rotation around a z-axis to determine incremental WLrotation angle, ΔØ_(INCR). FIG. 18B illustrates a simplified diagram ofa WL module 1801 that integrates a 3D MEMS gyroscope to measureincremental WL rotation angle. The module 1801 in FIG. 18A shows theplacement of a MEMS gyroscope 1820 on a PCB 1415. The module 1801 canhave a supporting baseplate 1303, a keyshaft 1305, and a removable cover1420 as described with respect to FIG. 13 and FIG. 14.

In some embodiments, a MEMS gyroscope module 1801 can be used todetermine the WL rotational angle. The angular velocities in x, y andz-axis, ω_(x), ω_(y) and ω_(z) are acquired from module 1801synchronously rotating with WL with a I2C bus communication protocol.The readings can be transmitted over a wireless network to a smartmobile computing device to determine if the angular velocity in z-axesexceeds a selected threshold value depending on the application. The WLrotation angles can be extracted from gyroscope signals usingconventional methods detailed in the prior art (See for example,Wearable Sensors, Fundamentals, Implementation and Applications, EdwardSazonov and Michael R. Neuman, 2014, Elsevier Inc., Encyclopedia ofNanotechnology, Bharat Bhushan, 2016, Springer Science Business MediaDordrecht, 1427-1440, which are hereby incorporated by reference intheir entirety).

In further embodiments, a MEMS 3D eCompass is used to measure the rateand angle of WL rotation. The MEMS 3D eCompass integrates both a 3-axisaccelerometer and 3-axis magnetometer to sense rotation in a singlemodule with a microcontroller. The magnetometer tracks the deviceorientation with respect to the Earth's magnetic field in 3 dimensions.The accelerometer and magnetometer data are used together to compute theincremental changes in WL rotation angle, ΔØ_(INCR).

FIG. 18C illustrates a simplified view of a module 1802 having a 3DeCompass 1840 to sense the angular rotation of a WL. The sensor module1802 includes a MEMS eCompass 1840 mounted on a PCB 1415. The module1802 can have a supporting baseplate 1303, a keyshaft 1305, and aremovable cover 1420 as described with respect to FIG. 13 and FIG. 14.

Similar to the WL module 1801, angular velocities in x, y and z-axis,ω_(x), ω_(y), and ω_(z) of a WL can be sensed by the module 1802 andtransmitted over a wireless network by way of a smart device I²C buscommunication protocol. If value of angular velocity exceeds a selectedthreshold, rotational data is normalized against calibrated WL magneticprofile data. The WL rotation angle can be extracted from eCompass datausing conventional methods (Wearable Sensors, Fundamentals,Implementation and Applications, Edward Sazonov and Michael R. Neuman,2014, Elsevier Inc., Encyclopedia of Nanotechnology, Bharat Bhushan,2016, Springer Science Business Media Dordrecht, which are herebyincorporated by reference in their entirety).

It will be apparent that a plurality of novel methods for measuringincremental WL rotation angle, Ø_(INCR), are disclosed herein. Variousmethods are based on real time analysis of a visual or audio signal of arotating WL or employing a WL sensor module that can include a dualmulti-axis MEMS accelerometer, a multi-axis MEMS gyroscope and/or amulti-axis MEMS eCompass, and others described above. One of thesemethods can be sufficient to reliably and accurately determine anincremental WL rotation angle in an embodiments.

In some embodiments, these methods can be used co-operatively to improvethe reliability and accuracy of the measurements of WL rotation angles.For example, a MEMS accelerometer and a MEMS gyroscope can be integratedin a WL module to determine WL rotation angles. An integrated WL modulecan be particularly useful if angular velocity changes are small andassociated with a drift during the course of a long measurement or ifchanges in linear acceleration along the y-axis of the accelerometerwould offset the tangential velocity computed. In another embodiment,the module 1801 and the module 1400 can be combined as one module suchthat the WL rotation angle is measured using a gyroscope and/or anactive marking such as an illuminated LED or a passive circular marking1410 to ensure a reliable rode length measurement during an anchoringoperation.

A system for measuring the rate and total length of rode release caninclude a processor, memory media, display, digital camera, human inputdevice, a speaker, and application programs operable to perform thevarious functions and provide a human interface. In some embodiments,the system can be a cellular smartphone having a processor, memorymedia, display, digital camera, human input device, speaker, andapplication programs operable to perform the various operations andprovide the human interface.

Disclosed methods can be performed using a single device such as asmartphone, a tablet computer and/or other mobile computing device. Asmartphone has capabilities to capture video frames, perform real timeanalysis of the video frames to compute an incremental WL rotationangle, the length and rate of rode release, and display these computedresults and other critical anchoring information to users.

Another aspect of the implementation of the disclosed methods includesincorporation of a wireless network to improve overall systemreliability and flexibility for safe anchoring. Data acquired fromvarious WL modules such as a module with microphones and/or MEMS sensorsdescribed above can be sent to a remote device extracted via a wirelessnetwork. A remote device can process these data to compute the lengthand rate of the rode released, can display real time values of theseparameters together with other critical anchoring parameters such asspeed of boat, distance from anchoring site, can also provide specificalerts to crew members.

In some embodiments, a commonly used wireless local network protocol802.11 or other wireless communication means such as Bluetooth, NFC(near field communication) Zigbee, Z-Wave, and/or a cellular networkprotocol such as 2G, 3G, 4G, LTE, 5G and others can be useful foranchoring applications. For example, with the presence of such awireless network, particularly those standard integrated in commercialoff the shelf devices that crew members are likely to have in theirpossession—WiFi, BlueTooth, NFC and cellular, the distribution offunctions across multiple devices can be advantageous. Having suchcommercial devices on a boat and access to a data network, functions ofData Analysis and Display Alert can be implemented in manyconfigurations and with many levels of redundancy as required.

Using various methods and apparatus disclosed herein, it is possible toconveniently measure the length of a rode released by a WL during thecourse of an anchor operation. Most boats have Global NavigationSatellite Systems (GNNS) installed so they can navigate properly on theopen sea. Most mobile phone and tablets also have Global PositioningSystem (GPS) transceivers allowing them to sense position via the GPSconstellation of satellites. Using the GPS positioning sensors of eitherthe boat or mobile devices, the velocity of a boat can also be measured.If both rode release and boat velocities can be displayed and/ordetected on the same computing device they can be compared in real time.Such a technique is highly advantageous to the helmsperson and skipperof a boat. Except for the large and expensive boats in the class ofcontainer ships, tankers, pleasure cruisers, etc. such capabilities havenot existed on the vast majority of boats.

During the course of an anchoring, it is important to know instantaneousrate of rode release, instantaneous boat speed, and total length of rodereleased, and total distance travelled by the boat from the targetanchor position. As described above, if the boat is moved faster thanthe rate of chain release, there is a likelihood of dragging the anchorfrom its initial target position. If, on the other hand, boat speed isrelatively low, rode can accumulate on the seabed in a looseconfiguration without securing the boat. Accordingly, after the anchoris dropped near vertically to its target position, subsequent chainrelease should be at a rate that exceeds boat velocity. Hence thesefunctionalities must be simultaneously monitored, and displayed in ahuman interface.

If the value of boat velocity falls outside a specific range, a visualand/or audio alarm can warn the helmsperson controlling the velocity anddirection of the boat. Total rode length released, total boat distancetravelled, rate of rode release and boat velocity can all be monitoredsimultaneously and displayed on a smartphone and/or tablet by each crewmember, skipper, and helmsperson via a wireless network to avoidpotential anchoring issues described above.

Various methods to use information relating to the position and/or speedof a boat, water depth, the rate of rode release, and the algebraic sumof rode length that has traveled through the WL gypsy to perform areliable and/or secure anchoring operation are disclosed. Boat speed,positional information and/or water depth can be obtained using methodssuch as GNSS, sonar, pitometer, mapping data, and others. A methods andsystems are disclosed to give crew members an ability to adjust theposition and speed of the boat in real time to maintain a cooperativerelationship between a selected rate of anchor rode release, boatvelocity, and boat position that is operable to effectuate a safe andreliable anchoring operation. These methods and systems can include ahuman interface having a display showing the real time ratio of the boatvelocity to the rate of anchor chain release. Human interface cancommunicate calculated and/or predetermined target values of variousparameter and alarms where a parameter value is outside a determinedrange.

In some embodiments, a method of simultaneously measuring boat speed,its distance from anchor (in units of measure relevant to the rodelength) together with the incremental rode released throughout theanchoring operation is disclosed. Boat position is measured via GNSSthrough the triangulation of readings from multiple satellites. Manyportable mobile devices such as smartphones and/or tablets within thewireless data network can provide position data of a boat.

Water depth is another critical parameter for anchoring operation, whichcan be measured by a crude sonar device mounted at the bottom of thehull near midship of a boat. The sonar device is particularly importantto prevent a boat touching to the surface of the sea bed in shallowwater. To compute the actual water depth at midship, a crew member mustadd the boat's draft (distance from surface to bottom of boat). Theresulting value can be entered into the application running on thesmartphone. Alternatively, during the course of dropping anchor at theanchor site there is a brief change in rode tension and WL rotationspeed at the point that the anchor reaches sea bed. In some embodiments,this discontinuity in rode tension can be used to determine water depthsince the rate and length of rode released is monitored continuously viavarious methods disclosed herein.

Another aspect of this disclosure is an application operable to providecrew members with critical real time control and measurement informationabout the state of an anchoring operation.

A preferred embodiment has a specific application that can be run on amobile device operable to acquire, compute, and display a boat position,distance from the anchor site, boat speed, and rode release rate andlength. The application acquires and stores the boat position relativeto a selected anchoring site. As the boat backs away from the selectedanchoring site, the application can update and display the instant boatposition, and can compute and display the real time distance betweenreal time boat position and the selected anchoring site. The applicationcan also display real time boat velocity, and a time-average and/or realtime speed at which the boat is moving from the anchoring site; theapplication can also display a continuously updated total length andreal time rate of rode release.

In this embodiment, the application is operable to compare the rate ofrode being released to the real time boat speed and/or the total lengthof rode that has been released to distance that the boat has moved fromthe anchoring site. If a real time value of the ratio between the boatspeed and rate of rode being released falls below a selected value,visual and/or audio alerts can be sent, displayed, or otherwise soundedto alert the helmsperson and/or crew to attend to the speed anddirection of the boat. In view of the disclosure above, those havingordinary skill in the art will recognize that the application canmonitor, detect, and alarm based on relatively more complex conditionscomprising the boat speed, rate of rode release, amount of rodereleased, distance between the boat and the anchoring site, and/orseabed depth profile.

The parameter values, alerts and alarms, and other information from theapplication executing on a first device can be sent (pushed) or accessed(pull) by various other computing devices used by other crew members(including a skipper, helmsperson, etc) by way of a wireless network.Depending on the embodiment, the architecture of these additionaldevices can be the same as the first device, or the various devices canbe heterogenous (e.g. they may be an Android tablet and/or smartphone, alaptop Windows computer, an Apple iPad or iPhone, and/or others).Because data, alerts, and/or alarms can be accessed and/or pushed to inthis manner, prospective and current anchoring issues or exigencies canbe promptly detected and avoided.

Various embodiments have a human interface operable for an operator tomanually enter the water depth, or an application can automaticallyacquire the water depth based on a geophysical location. The geophysicallocation can be sensed using GPS, GNSS, and/or other navigation means.The anchoring application can compute a total length of rode to releaseand/or remaining length to be released. When the total length has beenreleased, the crew is alerted to stop further rode release and to stopor disengage the boat engine.

FIG. 19A shows a screen shot 1900 from an application made to run on anApple iPad according to these teachings. The application displaysreleased chain 1905, rate of chain release 1910, distance from anchorsite 1915, and yacht speed 1920 in real time via wireless network basedon data received from a computing device performing the frame by frameimage analysis of video frames having a distinguishable marking on a WLCto determine incremental WL rotation angle as described above.

The user interface can include a graphic simulation of the boat on thewater as the anchor operation proceeds, an anchoring progress indicator,and/or synthetic speech announcing measurement data and milestonesduring anchoring. Audio alerts and/or cues can include sounds such asbeeps that can be loud or can increase or decrease in volume, frequency,or pitch depending on boat speed, rode speed, and/or difference inand/or between these parameters, depending on the embodiment. The userinterface can also include visual cues such as a flashing and/orblinking screen, colored indicators or color changes, including changesin the appearance of the value of a quantity or signal that can bealtered at a frequency proportional to values and/or differences inparameter values depending on boat and/or rode speeds and/or boatposition.

One embodiment of the instant disclosure utilizes the collected andwirelessly transmitted data to control the operation of the WL and/orboat engine throttle. A specialized device attaches to the WL controlbutton connections to enable up-down, on-off operation from a separatecomputing device. The buttons are simple closure devices so theinterface consists of simple relays controlled by a microcontrollerreceiving signals over a WiFi network. Integrating control over anengine throttle is a more complex task and can require a mechanicallycontrolled device attached via a mechanical linkage to the air intake ofa diesel engine. Such a device would again, be interfaced to amicrocontroller system with small robotic arm receiving control signalsvia the WiFi network.

FIG. 12 shows examples of visual cues displayed to users during ananchoring operation such as the detections of a WL, a marking on the WL,and WL rotation. There are embodiments where additional instructions canbe given the users to simplify the execution of the anchoring methodsdescribed herein. These instructions can provide further guidance to theuser under various circumstances including if a WLC can move out of acamera view when capturing video frames, if marking on a WLC and/or a WLmodule not detected from the video images captured, if the WL startsrotating and/or changes its direction of rotation during anchoring, ifthere is a change in stress in the rode detected (an indication of ananchor reached seabed). These alarms/alerts can be presented visuallyand/or vocally (such as in the form of beeps, sustained sounds and/orspeech) to enhance user experience and system accuracy and reliability.

FIG. 19B shows a screen shot from an application made to run on an AppleiPhone during an anchoring operation. Display image 1940 includesvarious user instructions to execute the methods disclosed hereinsmoothly. Two arrows indicating the directions of bow 1950 and stern1955 of a boat guide a crew member to orient the iPhone camera whencapturing video images of a WL. A circular WL Guide 1960 provides avirtual instruction on a screen for a crew member to maintain a WLcapstan image 1965 in full view within the boundary of the WL guide 1960and in a preferred WL size. In some embodiments, the WL guide can changecolor during the course of data analysis depending on the state of therotation detection algorithm (see FIG. 12). For example, the initial WLguide 1960 can be black. When a circle defining the outermost edge ofthe WLC is detected, the display shows the WL guide 1960 in yellow. Whena marking on the WLC (such as a black tape as seen in FIG. 12) isdetected, the WL guide 1960 can be displayed in green. A “video play”button 1980 at the bottom of the screen indicates that the system isready for measurement. When the button 1980 is selected, “video pause”text display appears on the screen to inform the crew member to stop themeasurement. A text display such as “Press Pause Button to PausePlayback” 1970 provides the crew member further instructions on nextsteps and/or warnings about a problem. A running meter 1975 displays theactual rode length as it is being measured. In some embodiments,additional information such as boat speed or boat distance from anchorsite (not shown in this screen image) can be displayed to inform thecrew members during anchoring.

Crew members at sea may not have an access to high speed internet duringthe deployment of the disclosed methods. Hence, the raw data obtainedduring the course of measurements and the associated metadata are saved,analyzed and stored in a local device database initially, and uploadedto a remote server database once access to the internet is available.The acquired data is generally uploaded to a remote data center facilityfor storage and further offline testing. The algorithms and parametersused in the disclosed methods are modified an ongoing basis at the datacenter facility comprising more powerful CV, AI and DSP libraries tofurther improve overall system reliability and accuracy. The datarecorded from various anchoring operations at different lighting and/orweather conditions, or different water depth by different crew memberson different types of boats with different types of windlasses can beexamined further to test and improve the performance of the algorithms.In some embodiments, the modified algorithms can be applied across allsystem deployments. In other embodiments, the algorithms can befine-tuned to use for a specific family of windlasses and/or gypsies. Infurther embodiments, the algorithms can be adapted to enhance themeasurement reliability on a specific type of a boat. In still furtherembodiments, a particular emphasis can be given to increase robustnessof detection and tracking of a characteristic marking on the WLC by theCV subsystem under changing anchoring conditions.

In the foregoing specification, various aspects are described withreference to specific embodiments, but those skilled in the art willrecognize that further aspects are not limited thereto. Various featuresand aspects described above may be used individually or jointly. Otheraspects of the invention, including alternatives, modifications,permutations and equivalents of the embodiments described herein, willbe apparent to those skilled in the art from consideration of thespecification, study of the drawings, and practice of the variousaspects. Further, various aspects can be utilized in any number ofenvironments and applications beyond those described herein withoutdeparting from the broader spirit and scope of the description. Thewritten description and accompanying drawings are, accordingly, to beregarded as illustrative rather than restrictive.

Although various embodiments have been presented and explained usingsimplified examples, it will be understood that various changes andmodifications are possible with regard to materials, shapes, anddimensions, without departure from the scope of the patent claims. Theembodiments and preferred features described above should be consideredexemplary, with the invention being defined by the appended claims,which therefore include all such alternatives, modifications,permutations and equivalents as fall within the true spirit and scope ofthe present disclosure.

What is claimed is:
 1. A method for determining a length of rodetraversing a gypsy of a windlass in real time during an anchoringoperation, based on accumulating a sum of signed incremental rotationangles of a windlass in real time with a computer, the methodcomprising: capturing early and later digital images including thewindlass and a trackable feature on the uppermost surface of thewindlass, at respectively early and later times, and saving the earlyand the later digital images in a computer memory; sensing an early anda later angular position of the trackable feature on the windlass in therespective early and later digital images using a computer visionalgorithm; detecting a difference between the early and the laterangular positions of the trackable feature on the windlass in real timewith a computer, wherein said difference between the angular positionsis a signed incremental rotation angle; adding the signed incrementalrotation angle to the sum of signed incremental rotation angles; andmultiplying the sum of signed incremental rotation angles by acalibration factor defining a proportionality between a length of roderelease and windlass rotation angle.
 2. The method of claim 1 whereinthe length of rode release is a total length of rode that has beenreleased and/or gathered during an entire anchoring operation.
 3. Themethod of claim 1 wherein the digital images are captured with a camerahaving a digital image sensor.
 4. The method of claim 1 furthercomprising a step of providing the trackable feature on a visible uppersurface fixed to the windlass, wherein the trackable feature is selectedfrom among: a marking; material comprising a pattern adhering to thevisible upper surface; a light emitting device; an area of the uppersurface having alphanumeric characters; and an area of the visible uppersurface having distinct contrast.
 5. The method of claim 1 furthercomprising steps operable to determine the calibration factor.
 6. Themethod of claim 5 wherein the steps operable to determine thecalibration factor comprise: supporting the digital camera in a positionwhere a field of view of the camera encloses a windlass capstan and aportion of a rode chain emerging from the windlass; providingapplication software having a user interface operable to show digitalcamera video images from the camera in real time on a touch screendisplay, superimpose a center alignment marking for the windlass capstanand a central alignment marking for the rode chain on the touch screendisplay showing digital camera video images, and receive user gesturesfor positioning and/or scaling the center alignment marking for thewindlass capstan onto a center of the windlass capstan in the digitalcamera video images, and positioning and/or scaling the centralalignment marking for the emerging rode chain onto a midline of theemerging rode chain in the digital camera video images; and computing aneffective windlass gypsy diameter based on the positioning and/orscaling of the center alignment marking for the windless capstan andcentral alignment marking for the emerging rode chain.
 7. The method ofclaim 1 wherein the capturing, the sensing, the detecting a difference,the adding, and the multiplying is performed with a mobile computingdevice comprising a digital camera, tangible media operable to storedata and instructions, a processor, a touch-sensitive display screen, anspeaker, and a wireless network communication interface, wherein themobile computing device is selected from among a smartphone, a tabletcomputing device, and a portable computer.
 8. A method of determining alength of rode chain traversing a gypsy of a windlass and emerging fromthe windlass in real time during an anchoring operation, the methodcomprising: providing a number of rode chain links in a unit length ofthe rode chain; supporting a digital camera in a position wherein thelength of rode chain emerging from the windlass is within the field ofview of the digital camera; capturing a sequence of digital video imagesfrom the digital camera and saving the digital video images of thesequence; analyzing each digital video image of the sequence in relationto previous digital video image(s) of the sequence with an optical flowanalysis algorithm to detect a number of chain links passing through thefield of view; and dividing the number of chain links passing throughthe field of view by the number of chain links per unit length of therode chain.
 9. Computer readable tangible media having stored data andinstructions for a mobile computing device to perform steps operable tomeasure a length of rode traversing a windlass gypsy of a boat and arate of rode being released and/or gathered by the windlass gypsy in aboat anchoring operation; the steps comprising: capturing an early and alater digital image of the windlass at respectively early and latertimes with a digital camera and saving the early and later digitalcamera images in a computer memory; sensing an early and a later angularposition of a trackable feature on the windlass in the respective earlyand later digital images with a computer vision algorithm; detecting adifference between the early and the later angular positions of thetrackable feature on the windlass in real time using the mobilecomputing device, wherein said difference between the angular positionsis a signed incremental rotation angle; adding the signed incrementalrotation angle to a sum of signed incremental rotation angles; andmultiplying the sum of signed incremental rotation angles by acalibration factor defining a length of rode that is releasedproportionate to an angle of windlass rotation.
 10. The computerreadable tangible media of claim 9 further comprising stored data andinstructions operable for a processor of the mobile computing device toperform further steps operable to determine the calibration factor, thefurther steps comprising: providing user notification operable to directa user to support a digital camera in a position wherein video imagesfrom the digital camera comprise the windlass capstan and a portion of arode chain emerging from the windlass; displaying the digital imagescomprising the windlass capstan and a portion of a rode chain emergingfrom the windlass in a screen display; superimposing a windlass capstanalignment target on the windlass capstan in the screen display andsuperimposing a chain alignment key on the rode chain in the screendisplay; receiving user input operable to move and/or scale thesuperimposed windlass capstan alignment target on the windlass capstanin the screen display and the chain alignment key on the rode chain inthe screen display wherein the capstan alignment target is positioned atthe center of the windlass capstan in the screen display and the chainalignment key is centered in the emerging rode chain in the screendisplay; and computing an effective windlass gypsy diameter based on thepositioning and/or scaling of the capstan alignment target and the chainalignment key.
 11. The computer readable tangible media of claim 10wherein the screen display is a touch screen display and user inputcomprises gestures on the touch screen display.
 12. The computerreadable tangible media of claim 9 further comprising stored data andinstructions operable for a processor of the mobile computing device to:acquire real time boat location coordinates from real time positionsensing means embedded in the mobile computing device; determine a realtime speed of the boat based on the boat location coordinates; determinea real time total distance of the boat from an anchor site based on theacquired boat location coordinates; display first information comprisinga comparison of the boat speed to the rate of rode being released inreal time in a human interface of the screen display; determine a realtime total length of rode released from the boat based on the product ofthe calibration factor and the sum of the incremental rotation angles;display second information comprising a comparison of the total lengthof rode released from the boat to the total distance of the boat fromthe anchor site in real time in a human interface of the screen display;send the first and/or second information over a wireless network to aremote computing device, wherein a remote helmsperson, skipper, and/orcrew member having the remote computing device can receive the first andsecond information in real time; and compute a real time value of arelationship comprising one or more parameters selected from among thereal time values of boat speed, the rate of rode being released, thetotal length of rode released from the boat, and the total distance ofthe boat from the anchor site; and provide a visual and/or audible alarmon the mobile computing device depending on the real time value of therelationship; send a signal and/or data characteristic of the alarm fromthe mobile computing device over the wireless network to a remotecomputing device having remote data and remote instructions operable toreceive the characteristic signal and/or data from the wireless networkand to effectuate a remote visual and/or audible alarm for a remotehelmsperson, skipper, and/or crew member having the remote mobiledevice.
 13. The computer readable tangible media of claim 12, furthercomprising the remote data and remote instructions operable for theremote mobile device to receive the signal and/or data sent from thewireless network and effectuate the remote visual and/or audible alarm.14. The computer readable tangible media of claim 9 wherein the data andinstructions are operable to be performed in a mobile computing devicecomprising the camera, tangible media operable to store the data andinstructions, a processor, a touch-sensitive display screen, a speaker,and a wireless network interface controller, wherein the mobilecomputing device is selected from among a smartphone, a tablet computingdevice, and a portable computer.
 15. A method of accumulating a sum ofincremental angles of windlass rotation to determine a length of rodetraversing a gypsy of a windlass in an anchoring operation, comprising:receiving a plurality of samples of a sound field in a directionalmicrophone fixed to the windlass, and storing a digital representationof each sound sample in tangible media; detecting a patterncharacteristic of a difference between a later and an early angularposition of the windlass in the digital representations of the samples;and extracting a signed incremental rotation angle of the windlass fromthe sound sample based on detecting the pattern; adding the signedincremental rotation angle to a sum of signed incremental rotationangles; and multiplying the sum of signed incremental rotation angles bya calibration factor defining a length of rode that is releasedproportionate to an angle of windlass rotation.
 16. The method of claim15 further comprising receiving a plurality of samples of a sound fieldin an omnidirectional microphone fixed to a central position of thewindlass, and using the sound samples from the omnidirectionalmicrophone to suppress omnidirectional background sound and/or improvethe pattern detection.
 17. Tangible media comprising instructions anddata operable for a computer to perform steps for measuring a length ofrode traversing a windlass gypsy and a rate of rode being releasedand/or gathered by the windlass gypsy in an anchoring operation, thesteps comprising: receiving a plurality of samples of a sound field witha directional microphone fixed on the windlass, and storing a digitalrepresentation of each directional microphone sound field sample intangible media; detecting a pattern characteristic of a differencebetween a later and an early angular position of the windlass in thedigital representations of the plurality of sound field samples from thedirectional microphone; and extracting a signed incremental rotationangle of the windlass based on the characteristic pattern detected;adding the signed incremental rotation angle to a sum of signedincremental rotation angles; and multiplying the sum of the signedincremental rotation angles by a calibration factor defining a length ofrode that is released proportionate to an angle of windlass rotation.18. Tangible media comprising operable instructions and data for aprocessor to perform steps for: capturing a plurality of digital imagesusing an image sensor; performing a computer vision algorithm operableto extract an amount and rate of angular rotation of a windlass from thedigital images; and determining a length and rate of rode release basedon the rate and the amount of angular rotation.
 19. Tangible mediacomprising anchoring data and instructions operable for a local mobilecomputing device to measure a real time rate and length of rodetraversing a windlass, wherein the local mobile computing deviceincludes a processor, tangible media operable to store data andinstructions, a digital camera operable to capture digital images of amember selected from the group consisting of the windlass and chainlinks of the rode, in real time, a touch-sensitive display screen, aspeaker, and a wireless network communication interface; the anchoringdata and instructions are operable for the processor to determine realtime information including a length of rode release and a rate of roderelease using the captured digital images; and the anchoring data andinstructions are further operable to communicate the real timeinformation from the local mobile computing device to a remote crewmember by sending the real time information from the local mobilecomputing device over a wireless network to a remote mobile computingdevice, wherein the remote crew member receives the information from theremote mobile computing device.
 20. The tangible media of claim 19wherein the captured digital images are used to sense an amount ofangular rotation of the windlass.
 21. Means for using a computing deviceselected from the group consisting of a smartphone comprising a digitalcamera and a tablet computer comprising a digital camera to measure alength of rode release from a windlass in real time using a sequence ofimages acquired with the digital camera during an anchoring operation.22. An apparatus operable for a crew member to measure a real timelength and real time rate of rode chain release through a windlass of aboat, the apparatus comprising: a processor; a camera operable tocapture sequential digital images comprising a trackable item selectedfrom among a trackable feature on the windlass and chain links emergingfrom the windlass gypsy, wherein the sequential images includeinformation operable for a processor to determine the real time lengthand rate of rode chain length released through the windlass; a networkinterface controller; and machine readable tangible media comprisingdata and instructions operable for a processor to perform steps for:determining the real time length of rode chain release and the real timerate of rode chain release using the sequence of digital video images;wherein the apparatus is operable to determine a real time speed of theboat based on determining a boat location and using the boat location tofind a real time speed of the boat and distance of the boat from ananchoring site; and comparing a value of the real time speed of the boatto a value of the real time rode chain release and sending an alarm ifthe ratio of these values exceeds a predetermined threshold alarm value.